.dt Useful Knowledge: 4th ed. Minerals. Vol 1 of 3, by William Bingley-A\
Project Gutenberg eBook
.de body {width:80%; margin:auto;}
// Transcriber’s notes in a nice box.
.de .tnbox {background-color:#E3E4FA;border:1px solid silver;padding: 0.5em;margin:2em 10% 0 10%; }
.de .box1 {border-style: solid; border-width:thick; padding:15px}
.de .font85 {font-size: 85%}
// max line length
.ll 72
// default indentation for .nf l blocks
.nr nfl 4
// Page numbering
// .pn off // turn off visible page numbers
.pn link // turn on page number links
// paragraph formatting, indent paragraphs by 1.0 em.
.nr psi 1.0em
.pi
// replace hyphen used in .pb with line drawing character so it connects in UTF-8.
.sr u .-.─.
// footnote
.dm fn-start
.ni
.fs 85%
.fn #
.dm-
.dm fn-end
.fn-
.fs 100%
.pi
.dm-
// include a cover image in HTML only
.if h
.il fn=cover.jpg w=600px
.ca
The cover image was created by the transcriber and is\
placed in the public domain.
.ca-
.sp 2
.pb
.if-
// 001.png
.sp 4
.h1
Useful Knowledge: 4th ed. Minerals. Vol 1 of 3
.sp 2
.if h
.rj
Frontispiece to Vol. I. see Page #237#.
.il fn=frontis.jpg w=600px id=frontis link=frontis-l.jpg
.ca
Comparative Height of Mountains, Cities and Lakes
British Islands\_\_\_Continent of Europe\_\_\_Islands\
not British\_\_\_Asia\_\_\_America
(Click on image to see a larger version.)
J. Shury sculp.
.ca-
.if-
.if t
[Illustration: Frontispiece to Vol. I. see Page #238#, #239#.
Comparative Height of Mountains, Cities and Lakes
British Islands –– Continent of Europe –– Islands not British\
–– Asia –– America
J. Shury sculp.]
.if-
// 002.png
.pn i
.sp 2
.pb
.sp 4
.nf c
USEFUL KNOWLEDGE:
OR
A FAMILIAR ACCOUNT
OF THE
VARIOUS PRODUCTIONS
OF
Nature,
MINERAL, VEGETABLE, AND ANIMAL,
WHICH ARE CHIEFLY EMPLOYED FOR THE USE OF MAN.
Illustrated with numerous Figures, and intended as a Work\
both of Instruction and Reference.
.nf-
.hr 10%
.nf c
BY THE
Rev. WILLIAM BINGLEY, AM. FLS.
LATE OF PETERHOUSE, CAMBRIDGE, AND AUTHOR OF ANIMAL BIOGRAPHY.
.nf-
.if h
.il fn=hawk.jpg w=300px
.if-
.if t
.nf c
[Illustration: Publisher’s Logo]
.nf-
.if-
.nf c
IN THREE VOLUMES.
VOL. I. MINERALS.
.nf-
.hr 10%
.nf c
FOURTH EDITION.
.nf-
.hr 10%
.nf c
LONDON: PRINTED FOR BALDWIN, CRADOCK, AND JOY;
HARVEY AND DARTON;
AND C. AND J. RIVINGTON.
.nf-
.hr 10%
.nf c
1825.
.nf-
// 003.png
.pn +1
.sp 2
.pb
.sp 4
.in 10
.nf l
\_\_\_C. Baldwin, Printer,
New Bridge-street, London.
.nf-
.in 0
// 004.png
.pn +1
.sp 2
.pb
.sp 4
.h2
PREFACE.
.hr 10%
The mode in which instruction has hitherto been
conveyed, on the peculiar subjects of the present
work, has chiefly been by small books, in question
and answer, denominated catechisms. But such,
however respectable in themselves, or however
advantageous for children, are wholly insufficient
for persons who are in search of extended knowledge,
and desirous of furnishing their minds with
useful information.
On these subjects there has not hitherto been
published any work in which they are collectively
to be found; nor could a knowledge of them be
obtained but by the consultation of many and
expensive writings. That they are generally important
to be known will not probably be denied.
It has consequently been the object of the author
to compress all the interesting information that
could be obtained respecting them, within as narrow
a compass, and at the same time to render
this information as entertaining, and as devoid of
technical words and phrases, as possible.
The scheme of the work will, it is hoped, be
found sufficiently simple. The passage in smaller
characters at the head of each article, is in general
// 005.png
.pn +1
so arranged as to reply to the questions, “What
is?” “What are?” or “How do you know?”
For instance: “What is flint?” (See Vol. I. p. #53:n90#.)
The answer will be found thus: “Flint is a peculiarly
hard and compact kind of stone, generally
of smoke-grey colour, passing into greyish white,
reddish, or brown. It is nearly thrice as heavy as
water, and, when broken, will split in every direction,
into pieces which have a smooth surface.”
The author is aware that, in many instances, the
definitions are defective: but this has, in general,
arisen from a necessity of rendering them short,
and at the same time of using such terms as would
be likely to convey information to the minds of
persons who have had no previous knowledge of
the systems of natural history.
After the definition, a further illustration sometimes
follows; and in the large characters will be
found a brief detail of the history and uses of the
object described. The articles are numbered, for
the greater convenience both of reference and
explanation, but particularly the latter. Thus,
under the explanation of Carbon, it is stated that
“in combination with oxygen (#21:n21#) it forms carbonic
acid (#26:n26#), and that it is the chief component
part of pit-coal (#217:n217#), petroleum (#213:n213#), and other
bituminous substances.” By a reference to the
// 006.png
.pn +1
numbers inserted, each of the words, against
which they stand, will be explained: whilst at least
three of them would otherwise have been incomprehensible
by the generality of unscientific readers.
It must be remarked that the reader will not
here find an account of every production of nature,
which is employed for the use of man, nor
even all the uses of such objects as are described.
The most important of the productions, and the
principal of the uses, are all that he trusts can
reasonably be required in a work of the present
extent. On this ground it is that a great number
of animals, which are in request only for food,
have been wholly omitted.
The figures that are inserted have been drawn
upon as small and economical a scale as was compatible
with a sufficiently accurate representation
of the objects to which they relate. If the reader
be desirous of reference to further illustration, he
will derive much satisfaction from the invaluable
figures of Mr. Sowerby in his British and Exotic
Mineralogy, and English Botany, and Woodville’s
Medical Botany; as well as from those in Dr.
Shaw’s General Zoology, and Bewick’s Histories
of Quadrupeds and British Birds. There are also
many figures of useful animals in the author’s own
work, entitled “Memoirs of British Quadrupeds.”
// 007.png
.sp 2
.pb
.pn +1
.sp 4
.nf c
ADVERTISEMENT
TO THE
THIRD EDITION.
.nf-
.sp 2
Since this work was first printed, the author has
made in it considerable improvements. The first
volume, particularly, contains many additional articles,
and more than half of it has been re-written.
The plates also have been re-engraved. For the plate
of the mountains a new drawing has been made,
that the scale might be extended, and many particulars
might be introduced which before were omitted.
For the plates of vegetables every drawing has been
corrected; and, in place of such figures as were most
defective, new ones have been inserted.
.in 2
.nf l
Charlotte-street, Bloomsbury,
London, 1st March, 1821.
.nf-
.in 0
// 008.png
.pn +1
.sp 2
.pb
.sp 4
.h2
EXPLANATION OF THE PLATES||OF THE||FIRST VOLUME.
.hr 10%
.nf c
FRONTISPIECE.
This is explained in pages #236#, #237#.
.sp 2
PLATE I.
.nf-
.ta r:6 h:40
Fig. |MINERAL DEPOSITS.
1. |Horizontal beds or strata.
|a. Veins or dykes.
2. |Bending strata.
3. |Minerals in detached masses.
4. |Disjoined strata.
|b. A fault.
.ta-
.sp 4
.nf c
PLATE II.
CRYSTALS, &c.
.nf-
.ta r:6 h:40
5. |Octohedron.
6. |Rough diamond.
7. |Profile of a brilliant-cut stone.
8. |Profile of a rose-cut stone.
9. |Plane of a table-cut stone.
10. |Plane and profile of the Pitt diamond.
11. |Dodecahedron.
12. |Rough garnet.
13. |Six-sided pyramids, joined base to base.
14 |Regular four-sided prism.
15. |Six-sided prism.
16. |Cube.
17. |Four-sided pyramid having a rhomb for its base.
.ta-
// 009.png
.pn +1
.sp 4
.nf c
PLATE III.
SECTION OF ROCKS.
I. Primitive Rocks.
.nf-
.ta r:6 h:40
Fig. |
1. |Granite.
2. |Gneiss.
3. |Mica-slate.
4. |Clay-slate.
|a. Lime-stone.
|b. Quartz.
5. |Primitive lime-stone.
.ta-
.sp 2
.nf c
II. Secondary Rocks.
1. Transition Rocks.
.nf-
.ta r:6 h:40
6. |Grey-wacka.
7. |Transition lime-stone.
.ta-
.sp 2
.nf c
2. Floetz Rocks.
.nf-
.ta r:6 h:40
8. |Old red sand-stone.
9. |Alternating strata of lime-stone and sand-stone.
.ta-
.sp 2
.nf c
III. Alluvial Deposits.
.nf-
.ta r:6 h:40
10. |Alluvial strata of clay, gravel, &c., &c.
.ta-
.sp 4
.hr 10%
.in 4
.ti -4
The BINDER is desired to insert all the Plates, except
the Frontispieces, immediately after the Explanations
in the respective Volumes.
.in 0
// 010.png
.pn +1
.sp 2
.pb
.sp 4
.if h
.il fn=plate-01.jpg w=600px id=pl-1
.ca
Pl. 1. Vol. I.
J. Shury. sculp.
Sections of Strata &c.
.ca-
.if-
.sp 2
.if t
[Illustration: Pl. 1. Vol. I.
Sections of Strata &c.
J. Shury. sculp.]
.if-
// 011.png
.pn +1
// 012.png
.pn +1
.sp 2
.if h
.il fn=plate-02.jpg w=600px id=pl-2
.ca
Pl. 2. Vol. I.
CRYSTALS &c.
.ca-
.if-
.if t
[Illustration: Pl. 2. Vol. I.
CRYSTALS &c.]
.if-
// 013.png
.pn +1
// 014.png
.pn +1
.sp 2
.if h
.il fn=plate-03.jpg w=600px id=pl-3
.ca
Pl. 3. Vol. I.
Section of Rocks. J Shury sculp.
.ca-
.if-
.if t
[Illustration: Pl. 3. Vol. I.
Section of Rocks.
J Shury sculp.]
.if-
// 015.png
.sp 2
.pb
// 016.png
.pn 1
.sp 4
.nf c
USEFUL KNOWLEDGE.
.nf-
.hr 10%
.h2
MINERALS.
.hr 10%
.h3
INTRODUCTION.
.sp 2
1. Minerals are natural bodies destitute of organization
and life: and Mineralogy is that branch of
natural science which treats of the properties and relations
of such bodies.
.sp 2
.h4
MINERAL DEPOSITS.
2. If we penetrate beneath the surface of the earth, we
observe there a very remarkable arrangement. Instead of
a generally uniform appearance, as we see on the surface,
we pass through divers substances, as clay, gravel,
sand, and numerous others, deposited in beds or strata
of various thickness, from a few inches to a great many
feet (#Pl. I. Fig. 1:pl-1#). These lie, for the most part, nearly
horizontal: but in some instances, particularly in mountainous
countries, they take different degrees of inclination;
and, in places where the country consists of
gently sloping hills and vales, the beds have a waving
or bending form (#Pl. 1, Fig. 3:pl-1#). The strata of which the
earth is composed, as deep as the curiosity or the necessities
// 017.png
.pn +1
of mankind have induced them to explore,
satisfactorily demonstrate the wisdom which has been
displayed in the arrangement of materials requisite for
the use of men and animals.
The first layer is frequently a rich, black mould,
formed almost wholly of animal and vegetable remains.
This yields sustenance to the vegetable productions;
and thereby becomes the actual, though not the immediate,
support of the whole animal creation.—Beneath
this is often found a thick bed of clay, that furnishes to
man a substance of which to make bricks, tiles, various
kinds of pottery, and innumerable other articles for the
comfort of social life.—Next are deposited vast beds of
gravel, that are of use in numerous points of view.—Underneath
this are the infinitely varying strata of sandstone,
limestone, &c. which not only serve for the construction
of buildings, and for other important purposes,
but also frequently surround mines which contain the
valuable metals.—Beneath a slaty stratum are usually
discovered those immense beds of coal so requisite for
the comfort, and, in some situations, even for the existence
of man.
These strata, it is true, are not always found together,
nor are they always discovered in the same order; but
the statement will suffice to show the general nature of
their arrangement.
3. Minerals are sometimes observed in detached
masses of various size, and situated at various depths in
the earth (#Pl. I, Fig. 1:pl-1#).
4. They are also found in a kind of natural clefts
which cross the regular mineral beds or strata in different
directions (#Pl. I, Fig. 1, a:pl-1#, #Pl. I, Fig. 4, b:pl-1#). When these
// 018.png
.pn +1
contain metallic ores, they are styled veins; but when
they contain only stony or earthy matters, the miners
call them dykes. They vary much both in magnitude
and length. Six thousand feet are considered an unusual
length for veins, though, in some instances, veins
have been traced upwards of four miles. Few veins
extend more than 1200 feet below the surface of the
mountains in which they are situated. They are
usually much inclined; but they sometimes descend
in a direction parallel with the beds of rock in which
they occur.
5. At the places where dykes or veins pass through
the earth, they occasionally disjoint the strata in a very
singular manner (#Pl. I, Fig. 4:pl-1#). Some of the coal strata,
for instance, are thrown down or raised on one side of
a dyke upwards of a hundred yards; and the miner,
after penetrating through this dyke, instead of finding
the same coal again, meets, on the opposite side, with
beds of stone or clay. Hence he is frequently at a loss
how to proceed in searching for the coal of which he
is in pursuit; and hence it is that to such dykes the
peculiar name of faults has sometimes been given.
6. In England the metallic ores are generally found
in veins, that form a considerable angle with the regular
strata. This in Cornwall is uniformly the case.
And it is remarkable, concerning the veins of tin and
copper of that county, that they run in a direction
nearly east and west; whilst the dykes, or veins of
other substances, run for the most part north and south.
7. The thickness of veins, and the quantity and
quality of the ores they contain, differ in every mine.
Some are only a few inches wide, whilst others extend
// 019.png
.pn +1
to the width of several feet. The vein at Dalcooth
mine, in Cornwall, varies from two or three to forty feet
and upwards; and, in some parts, it contracts so as to
be little more than six inches across.
8. In Cornwall the first traces of tin and copper are
usually found at the surface of the ground, and thence to
the depth of 80 or 100 feet beneath; and it is said that
no miner has ever yet seen the bottom of a vein, although
several have been wrought to the depth of more than
1000 feet. The veins of these metals have, in some instances,
been worked to the length of three or four miles.
9. It is frequently observed that metallic veins are
separated, from the substances they intersect, by a thin
wall, or lining, of minerals different from these substances,
and also by a layer of clay on each side of the
vein. It is also remarked that the same substance which
forms the outer coat of the vein is often intermixed
with the ore, or forms layers alternately with it. This
has usually the denomination of matrix or gangue.
10. There are few mines of any considerable depth
that would not be flooded with water from internal
springs were not means adopted for drawing off this
fluid. The steam engines that are employed for this
purpose in some of the Cornish mines are so powerful
as to discharge incessantly, both by night and day, a
quantity of water, equal to at least 1000 gallons, or
near twenty hogsheads, every minute.
.sp 2
.h4
SYSTEMATIC ARRANGEMENT OF MINERALS.
11. To a superficial observer, perhaps nothing would
appear more easy than to describe a mineral. This,
// 020.png
.pn +1
however, is by no means the case. The same general
appearance sometimes prevails in substances that are
very different from each other; and the same stone,
in its different states, is often extremely varied in its
appearance. To these difficulties it must be added,
that the combinations of mineral substances are multiplied
to a great extent. A little application, however,
particularly if the student be possessed of a collection
of arranged and named specimens, which he will have
no difficulty in procuring at a reasonable price, will
enable him to overcome all the obstacles that otherwise
might impede his progress in beginning to acquire a
knowledge of this interesting science.[#]
12. The most simple and natural division of minerals
is into four classes, of, 1. Stones; 2. Salts; 3. Combustibles;
and, 4. Metals; and the following table,
which has chiefly been arranged from the system of
Werner, the well-known German mineralogist, will
exhibit a tolerably correct outline of the classification
of these substances. To reduce the whole within the
compass of a single page, many of the families, however,
have necessarily been omitted.
.pm fn-start // A
Such collections are supplied by Mr. Mawe, No. 149,
Strand, London. His terms, for collections containing from 100
to 200 specimens, are 5 guineas; from 200 to 300 specimens,
10 guineas; and from 300 to 400 specimens, 15 guineas.
For collections containing from 350 to 400 specimens, more
select, and comprising a better suite of precious stones, he
charges from 20 to 30 guineas; and for larger collections, from
50 to 100 guineas. At the particular request of the author, Mr.
Mawe has arranged a few collections of minerals, and numbered
them in such manner as to correspond with, and illustrate the
present volume.
.pm fn-end
// 021.png
.sp 2
.pb
.pn +1
.sp 2
.if h
.dv class=box1
.il fn=outline-01.jpg w=600px
.dv-
.if-
.if t
.in 1
.nf b
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_PRINCIPAL\_SPECIES.
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_Diamond.\_\_\_\_\_Diamond.
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_Zircon.\_\_\_\_\_\_Jargoon.
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_\_\_{\_Oriental\_sapphire.
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_Ruby.\_\_\_\_\_\_{\_Oriental\_ruby.
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_Scratch\_{\_\_\_\_\_\_\_\_\_\_\_\_{\_Emery.
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_glass.\_{
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_{\_Schorl.\_\_\_\_{\_Topaz.
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_\_\_{\_Emerald.
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_{\_Garnet.\_\_\_\_\_\_Precious\_garnet.
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_\_\_{\_Crystal.
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_{\_Quartz.\_\_\_\_{\_Flint.
\_\_\_\_\_\_\_\_\_\_\_\_\_{\_I.\_\_EARTHY.\_\_\_{\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_\_\_{\_Agate.
\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_Opal.
\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{
\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_{\_Clay.\_\_\_\_\_\_\_Pure\_clay.
\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_{\_Clay\_slate.\_Roofing\_slate.
\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_Will\_not\_{\_Mica.\_\_\_\_\_\_\_Muscovy\_glass.
\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_scratch\_\_{\_Soapstone.\_\_Fuller’s\_earth.
\_{\_I.\_STONES\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_glass.\_\_\_{
\_{\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_Talc.\_\_\_\_\_{\_Talc.
\_{\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_Asbestos.
\_{\_\_\_\_\_\_\_\_\_\_\_{
\_{\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_Limestone.
\_{\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_Lime.\_\_\_\_\_{\_Phosphat\_of\_lime.
\_{\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_\_{\_Fluor\_spar.
\_{\_\_\_\_\_\_\_\_\_\_\_{\_II.\_\_SALINE.\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_\_{\_Alabaster.
\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{
\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_Barytes.
\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_Strontian.
\_{
\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_Alumine.\_\_\_\_Alum.
\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{
\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_Magnesia.\_\_\_Epsom\_salt.
\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{
\_{\_II.\_SALTS.\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_Soda.\_\_\_\_\_{\_Common\_salt.
\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_\_{\_Borax.
\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{
\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_Potash.\_\_\_\_\_Nitre.
\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{
\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_Ammonia.\_\_\_\_Sal-ammoniac.
\_{
\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_Sulphur.\_\_\_\_Sulphur.
\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{
\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_\_{\_Naphtha.
\_{\_III.\_COMBUSTIBLES\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_Bitumen.\_\_{\_Coal.
\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_\_{\_Jet.
\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{
\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_Graphite.\_\_\_Black-lead.
\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{
\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_Resin.\_\_\_\_\_\_Amber.
\_{
\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_Platina.\_\_\_\_Platina.
\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_Gold.\_\_\_\_\_\_\_Gold.
\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_Mercury.\_\_\_\_Mercury.
\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_Silver.\_\_\_\_\_Silver.
\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_I.\_MALLEABLE.\_\_\_\_\_\_\_\_\_{\_Copper.\_\_\_\_\_Copper.
\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_Iron.\_\_\_\_\_\_\_Iron.
\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_Tin.\_\_\_\_\_\_\_\_Tin.
\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_Lead.\_\_\_\_\_\_\_Lead.
\_{\_IV.\_METALS.\_\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_Nickel.\_\_\_\_\_Nickel.
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_Zinc.\_\_\_\_\_\_\_Zinc.
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_Arsenic.\_\_\_\_Arsenic.
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_Bismuth.\_\_\_\_Bismuth.
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_II.\_BRITTLE.\_\_\_\_\_\_\_\_\_\_{\_Cobalt.\_\_\_\_\_Cobalt.
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_Manganese.\_\_Manganese.
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_&c.\_&c.
.nf-
.in 0
.if-
// 022.png
.pn +1
.sp 2
13.To complete a general view of the different
productions of the mineral kingdom, it is requisite to subjoin a
tabular arrangement of the various kinds of rocks.
.sp 2
.if h
.dv class=box1
.il fn=outline-02.jpg w=600px
.dv-
.if-
.if t
.in 1
.nf b
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_SPECIES.
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_1.\_Granite.
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_2.\_Gneiss.
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_3.\_Mica\_slate.
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_4.\_Clay\_slate.
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_5.\_Primitive\_limestone.
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_6.\_Primitive\_trap.
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_7.\_Serpentine.
{\_I.\_\_PRIMITIVE.\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_8.\_Porphyry.
{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_9.\_Sienite.
{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{10.\_Topaz\_rock.
{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{11.\_Quartz\_rock.
{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{12.\_Primitive\_flinty\_slate.
{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{13.\_Primitive\_gypsum.
{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{14.\_White\_stone.
{
{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_1.\_Transition\_limestone.
{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_I.\_TRANSITION\_\_\_\_\_\_{\_2.\_Transition\_trap.
{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_ROCKS.\_\_\_\_\_\_\_\_{\_3.\_Grey\_wacke.
{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_4.\_Transition\_flinty\_slate.
{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_5.\_Transition\_gypsum.
{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{
{\_II.\_\_SECONDARY.\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_1.\_Old\_red\_sandstone.
{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_2.\_Floetz\_limestone.
{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_3.\_Floetz\_gypsum.
{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_4.\_Second,\_or\_variegated\_sandstone.
{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_5.\_Second\_floetz\_gypsum.
{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_II.\_FLOETZ\_\_\_\_\_\_\_\_\_{\_6.\_Shell\_limestone.
{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_ROCKS.\_\_\_\_\_\_\_{\_7.\_Third\_sandstone.
{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_8.\_Rock\_salt.
{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_9.\_Chalk.
{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{10.\_Floetz\_trap.
{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{11.\_Coal.
{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{12.\_Newest\_floetz\_trap.
{
{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_1.\_Peat.
{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_2.\_Sand\_and\_gravel.
{\_III.\_\_ALLUVIAL.\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_3.\_Loam.
{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_4.\_Bog\_iron\_ore.
{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_5.\_Calcareous\_tufa,\_&c.
{
{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_1.\_Burnt\_clay.
{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_I.\_PSEUDO\_VOLCANIC\_{\_2.\_Porcelain\_jasper.
{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_ROCKS.\_\_\_\_\_\_\_\_{\_3.\_Earth\_slag.
{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_4.\_Columnar\_clay\_ironstone.
{\_IV.\_\_VOLCANIC.\_\_{\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_5.\_Polishing\_slate.
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_II.\_TRUE\_VOLCANIC\_\_{\_1.\_Stones\_and\_ashes.
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_\_\_\_\_\_\_ROCKS.\_\_\_\_\_\_\_{\_2.\_Lava.
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_{\_3.\_Matter\_of\_muddy\_eruptions.
.nf-
.in 0
.if-
// 023.png
.pn +1
\_
.sp 2
14. For the purpose of ascertaining the names and
characters of minerals, attention must be paid to their
form, surface, lustre, fracture, or the appearance of their
internal surface when broken; structure, transparence,
streak, or the mark left when scratched by any hard
body; stain, or trace left when rubbed upon paper;
cohesion, whether solid, friable, or fluid: hardness, or the
resistance which they oppose when scratched; tenacity,
or the resistance which they oppose to the stroke of a
hammer; flexibility, or their property of bending without
breaking; feel, or the sensation communicated by their
surfaces when handled; smell, taste, adherence to the
tongue, sound, specific gravity, or weight in comparison
with that of water; colour and electricity.
15. To ascertain the chemical properties of minerals,
one of the most important instruments is the blow-pipe.
This is a tube which terminates in a cavity as fine as a
small wire, and through which the air is forced, and
made to play upon the flame of a candle. The flame is
thus concentrated, and directed against small particles of
the mineral to be examined, which is placed upon a bit of
charcoal in a spoon of platina or silver. The air is forced
into the blow-pipe by the mouth of the person using it,
or by bellows attached to it for that purpose. Under
this operation we have an opportunity of trying the action
of other bodies upon minerals at a very high temperature;
and the properties which these experiments bring
into view enable us, in many cases, to ascertain, not only
the nature, but even the component parts, of minerals.
.sp 2
.h4
SIMPLE MINERAL SUBSTANCES.
16. As a necessary introduction to the study of minerals,
it is requisite to describe, in a brief manner, such
// 024.png
.pn +1
simple substances as form their constituent parts. Few
of these, it is true, are to be found in a separate, uncombined
state; yet that they do exist, and that they are
to be obtained from the minerals with which they are
united, we have the proof of every day’s experience.
.sp 2
.h5
UNCONFINABLE FLUIDS.
17. There are some kinds of unconfinable fluids, the
existence even of which is manifested only by their
contact with other bodies, or becoming separated from
them. They are of a nature too subtile to be collected
or confined in our vessels for the purpose of examination,
and the investigation of their properties has consequently
been attended with peculiar difficulty. Those
at present known are caloric, light, electricity, and magnetism;
but of these the first only is immediately connected
with the subjects of our present investigation.
18. Caloric.—Every one is acquainted with the different
sensations of heat and cold. That matter which
produces on our bodies the sensation of heat has the
name of Caloric; heat being only an effect, of which
caloric is the cause. This is extended in a greater or
less degree through the whole extent of space, and
penetrates into the interior of even the most solid
bodies: in so doing it expands the particles of which
they are composed, augments their bulk, and diminishes
their solidity. The sun is the principal fountain
from which the earth is supplied with this fluid; and it
passes thence to us at the rate of 12,000,000 of miles
per minute. The defect of caloric in any substance
occasions the sensation called cold.
Were the world deprived of caloric, every species of
organized being would, from that moment, cease to
// 025.png
.pn +1
exist. It is the cause of all fluidity: to it every production
of the earth has been most essentially indebted,
even for its form and structure; and in no respect do
the power and goodness of the Almighty appear more
conspicuous than in the creation, dispersion, and continuance,
of this most subtile and astonishing fluid.
19. All the various substances with which we are
acquainted must be considered either as solid or fluid.
Every substance is defined to be a solid in which the
parts are so united or connected that it requires an
external force to separate them. A fluid, on the contrary,
is a body the parts of which are so loosely connected
that they not only yield easily to any force impressed
upon them, but also move freely amongst each
other; and every fluid is a combination of caloric with
some other substance.
20. Fluids are of two kinds: one of these, called
liquids, have, when at rest, a smooth and distinct surface,
and are distinguishable both by the sight and
touch; the other, denominated gas, or gaseous fluids,
have the appearance of air, and are not perceptible
either to the sight or touch, except under certain circumstances.
The latter are principally oxygen (#21:n21#),
azote or nitrogen, and hydrogen (#45:n45#). We shall at
present have occasion to speak only of the first.
.sp 2
.h5
GASEOUS FLUIDS.
21. Oxygen, like caloric, is a fluid never found in
an uncombined state. It forms one of the component
parts of the air that we breathe, and of the water we
drink; but it approaches nearest to a state of purity in
combination with caloric (#18:n18#), when it has the name of
oxygen gas. It was formerly called vital air, because
// 026.png
.pn +1
no breathing animal can live for a moment in any air
or gas which has not in it a mixture of oxygen; every
kind of combustible burns with great splendour in it,
and without it ceases to burn. It unites with a great
number of substances, and changes both their appearance
and properties in a very remarkable manner. Of
the metals it entirely destroys the metallic lustre, and
gives them an earthy form and texture. Substances in
this state have the name of oxides.
Lead, for instance, combined with oxygen becomes
the well-known red and heavy substance used by
painters, under the name of minium or red lead (#239:n239#).
This, if deprived of its oxygen, loses its red colour,
and returns to its former metallic state. Some of the
metals are oxidized by merely being exposed to
moisture. Thus the rust which is so readily contracted
by iron is an oxide of that metal, produced by its attracting
oxygen from the air or from water.
.sp 2
.h5
ACIDS.
22. It is one of the most remarkable properties of
oxygen to impart to most of those bodies called acids
their peculiar character of acidity. Oxygen does not
itself possess the properties of an acid, nor is it an
essential ingredient in all acids, though it is the acidifying
principle in the greater number of them.
23. Acid is a word originally synonymous with
sour. It has, however, been gradually extended in
its signification, and now comprehends all substances
possessed of the properties of exciting upon the tongue
the sensation called sour; of changing the blue colours
of vegetables to red; of uniting with water in almost
any proportion; of combining with alkalies (#42:n42#), metallic oxides,
// 027.png
.pn +1
and earths, and of forming with them
certain compounds called salts.
24. Sulphuric Acid, or Spirit of Vitriol, as it is commonly
called, is a liquid of a somewhat oily consistence,
transparent and colourless as water, formed by a combination
of oxygen (#21:n21#) with sulphur (#46:n46#). Like other
acids, it never occurs in nature in a pure state, for it
can no sooner be formed than it unites with earths (#31:n31#),
alkalies (#42:n42#), or metals, and forms, with them, several
well-known salts, which have the name of sulphats.
Thus alabaster (#192:n192#) and Epsom salts (#199:n199#) are respectively
formed by an union of sulphuric acid with
lime and magnesia, and are denominated by chemists
sulphat of lime and sulphat of magnesia. In like
manner, blue vitriol (#209:n209#) is sulphat of copper; green
vitriol (#208:n208#), sulphat of iron; and white vitriol (#210:n210#),
sulphat of zinc.
25. Phosphoric Acid is produced by a combination of
oxygen (#21:n21#) with phosphorus (#47:n47#); and, when obtained
in a state of purity, is not a fluid, but a white and flaky
substance. This acid, when combined with mineral
productions, forms those salts which have the name of
phosphats. It is very soluble in water; and, in dissolving,
makes a hissing noise, similar to that produced by
plunging hot iron into water.
26. Carbonic Acid is a compound of oxygen (#21:n21#) and
carbon, or pure charcoal (#48:n48#): and in a state of gas (#20:n20#)
it forms a constituent part of the atmospheric air. It is
also emitted in great abundance from wine, beer, and
other liquors, in a state of fermentation, and is sometimes
found in the lowest parts of mines, where it is
known to the miners by the name of choke damp, from
the circumstance of its immediately extinguishing
// 028.png
.pn +1
flame, and suffocating all animals that are immersed in
it. This gas, which was formerly called by chemists
fixed air, is about twice the weight of common air. In
combination with lime it forms chalk, marble, and limestone;
and it constitutes part of several other mineral
substances, which are thence denominated carbonats.
27. Fluoric Acid is a gas of very singular nature,
which is held in combination with lime, in the Derbyshire
or fluor spar (#194:n194#); and may be separated from it
by pouring sulphuric acid, or spirit of vitriol (#24:n24#), upon
powdered spar, in a leaden vessel called a retort,
and applying to it a gentle heat. The salts formed by
fluoric acid have the name of fluats.
28. The Boracic is a peculiar kind of acid, which, in
combination with soda (#200:n200#), forms the substance that
we import from the East Indies under the name of
borax (#204:n204#). When extracted from borax this acid does
not assume the form of a fluid, but appears in thin six-sided
scales or flakes, of white colour, which adhere
slightly together, and feel somewhat greasy in handling.
To the taste it is at first sour, then bitterish; and at last
it leaves an agreeable sweetness on the palate.
29. Muriatic Acid is a gas formed by the combination
of oxygen (#21:n21#) with some base that is not yet
known. It is an invisible and elastic fluid, which, in
mechanical properties, resembles common air, and has
a pungent and very peculiar smell. This gas unites
with alkalies (#42:n42#), earths (#31:n31#), and the oxides (#21:n21#) of
metals; and with them forms the compounds called
muriats, of which common salt, or muriat of soda (#202:n202#),
is one of the principal. The liquid muriatic acid, or
muriatic acid gas combined with water, is frequently
denominated spirit of salt (#202:n202#).
// 029.png
.pn +1
30. Nitric Acid is a compound of oxygen and azote,
or nitrogen, in the proportion of twenty-five parts, by
weight, of the latter to seventy-five of the former. It
is one of the constituent parts of nitre, or saltpetre
(#206:n206#); and, in a pure state, is transparent and colourless,
like water. By the action of light, however, it
soon becomes yellow; and, if exposed to the air, it
emits yellow fumes, which even tinge the air of the
same colour. To the taste it is extremely acid. It dyes
the skin a yellow colour, which is very difficult to be
removed; and it is so corrosive as to destroy almost
every substance into which it penetrates. If poured
upon oils, it sets them on fire. With various bases it
forms compounds called nitrats. This acid, which
hitherto has never otherwise been obtained than mixed
with water, is chiefly known in commerce by the name
of aqua fortis (#206:n206#).
.sp 2
.h5
EARTHS.
31. The solid contents of the globe are composed of
several elementary substances, amongst which have been
enumerated no fewer than nine different kinds of earth:
.in 4
.nf l
1. Silex.
2. Alumine.
3. Zircon.
4. Glucine.
5. Yttria.
6. Barytes.
7. Strontian.
8. Lime.
9. Magnesia.
.nf-
.in 0
These, when freed from foreign admixture, are, for
the most part, of white colour, not soluble in water,
not combustible, and do not exceed four times the
weight of water.
32. The whole of these earths have, till lately, been
considered simple and uncombined substances; but, by
the discoveries of Sir Humphrey Davy, it has been ascertained
that four of them have a metallic basis, and
are in fact metallic oxides, or compounds consisting of
// 030.png
.pn +1
a metal united with oxygen (#21:n21#). These, which have
the same affinity with their respective bases as rust has
to iron, are silex, lime, barytes, and alumine. Until,
however, some further light be thrown upon their nature
and constitution, they must continue to hold their
former situation of simple earths.
33. Silex, or Siliceous Earth, is the basis of all substances
known by the name of quartz and silex (#76:n76#).
In a state of nature it has never been found pure; but,
in combination with other substances, it abounds in
almost every country of the globe. Common flint (#90:n90#)
contains ninety-seven parts in a hundred of silex: it
consequently has given its name to this earth, silex
being the Latin word for flint. When purified it is a
white powder, the particles of which are harsh to the
touch, as if they consisted of very minute grains of
sand. It is not quite three times as heavy as water,
and has neither taste nor smell. Water will not dissolve
it, nor any kind of acid, except fluoric. Sir H.
Davy has discovered it to have a metallic basis, to
which he has given the name of silicium.
34. Alumine is a kind of earth, so called from its
forming the basis of alum (#197:n197#). It is soft, compact,
and tenacious; about twice the weight of water, and,
when breathed upon, has a smell which is peculiar to
all clayey productions. In the fire it shrinks, and becomes
so hard as even to yield sparks when struck
against steel. It readily absorbs water, and is dissolved
by most acids. Some writers state that pure alumine
has been discovered in a native state near Halle, in
Germany. It is found in a crystallized form, and
nearly in a state of purity, in the Oriental ruby and
sapphire. The name of argil, or clay, has sometimes
// 031.png
.pn +1
been applied to it; but, in mineralogy, this name has
usually been given to a mixture of alum, quartz, and
other substances. Sir H. Davy has obtained from
alumine a metallic basis, called aluminum.
35. Zircon, when freed from those substances with
which it is combined, is a white and somewhat rough
powder, insipid to the taste, insoluble in water, and
about four times as heavy as that fluid. It is found in
the two kinds of precious stones called jargoon and
hyacinth, and has not hitherto been applied to any
useful purpose.
36. Glucine is a kind of earth of peculiar nature,
which is found in the emerald and beryl, and, when
purified, forms a soft and white powder, without smell,
and of sweetish taste. To the last of these qualities it is
indebted for its name, which is derived from a Greek
word signifying sweet. It is somewhat unctuous to the
touch, and about three times as heavy as water. The uses
of this earth, whatever they may be, are not known.
37. Yttria is an earth which, among other particulars,
differs from glucine by its weight, as it is nearly five
times heavier than water. In a natural state it occurs
as the basis of a black Swedish mineral, called gadolinite.
When cleansed, by chemical process, from all its
impurities, it is a fine, white, and inodorous powder.
38. Barytes is a white, porous, and very heavy earth,
which can only be obtained pure by chemical process.
It is easily reduced to powder, and is soluble in all
kinds of acids. To the taste it is harsh and caustic;
and, if taken into the stomach, proves an extremely
virulent poison. In some respects it agrees with the
alkalies (#42:n42#), particularly in its property of changing
blue vegetable colours to green, and in corroding, like
// 032.png
.pn +1
them, though with less energy, all kinds of animal
substances. From these circumstances it has sometimes
been denominated an alkaline earth. Saturated
with sulphuric (#24:n24#) and carbonic acid (#26:n26#), it constitutes
the minerals denominated sulphat and carbonat of
barytes (#196:n196#). It has been discovered to have a metallic
base, which is called barium.
39. Strontian is an earth which, like barytes, is not
found otherwise than in combination with sulphuric and
carbonic acids. It occurs in various parts of the world,
and, when purified, forms a porous mass of greyish
white colour, acrid taste, and somewhat alkaline nature.
This earth converts vegetable blue colours to green,
but does not act so strongly on animal bodies as barytes,
nor is it poisonous, like that substance.
40. Lime, the basis of all those substances which are
denominated calcareous, is only to be obtained in a state
of purity by artificial process. Combined with carbonic
acid (#26:n26#) it forms limestone (#140:n140#), chalk, and marble;
all of which are capable of being converted into lime by
burning. Lime may also be obtained from oyster and
other sea shells. When pure, it is of white colour, and
moderately hard substance, though it is easily reducible
to powder. Its taste is burning and acrid; and, like
the alkalies, it changes vegetable blue colours to green.
It has likewise the property of corroding and destroying
animal substances. Lime, when pure, absorbs water
rapidly, becomes hot, and falls into powder. Even if
exposed to the open air it gradually attracts moisture,
and assumes a powdery form; soon after which it becomes
saturated with carbonic acid (#26:n26#) from the atmosphere,
and is thereby again converted into carbonat
of lime (#140:n140#). It occurs abundantly in almost every
// 033.png
.pn +1
country, but always in combination with some acid,
carbonic (#26:n26#), sulphuric (#24:n24#), boracic (#28:n28#), fluoric (#27:n27#),
or phosphoric (#25:n25#). This substance has a metallic basis,
which has been denominated calcium.
41. Magnesia is a light and perfectly white kind of
earth, of soft powdery appearance, without taste or
smell, and somewhat more than twice as heavy as water.
It is not found in this pure state in nature, but may be
prepared from Epsom salt, which consists of magnesia
in union with sulphuric acid (#24:n24#). The slightly acrid
taste that is perceptible in the magnesia used in medicine
arises from a portion of lime which it contains.
This substance does not dissolve in water, but is soluble
in every kind of acid. It has the property of changing
delicate blue colours to green.
.sp 2
.h5
ALKALIES.
42. Alkalies are substances which enter into the composition
of several kinds of minerals, and are known by
their property of changing the colour of blue vegetable
juices to green, and by a peculiarly acrid, caustic, and
nauseous taste, which it is impossible to describe, but
which, after it has been once experienced, will easily be
recollected. Alkalies corrode and dissolve animal substances,
and unite with oil and fat in such manner as to
form the well known compound called soap. They
readily dissolve in water; and, when mixed with acids,
form what have been denominated neutral salts.
43. The alkalies at present known are three in number;
potash (#205:n205#), soda (#200:n200#), and ammonia (#207:n207#). Of
these the two former, although till lately they have
been considered simple substances, have been shown
by Sir H. Davy to have metallic bases.
// 034.png
.pn +1
.sp 2
.h5
SIMPLE COMBUSTIBLES.
44. By this term we are to understand all those mineral
substances, capable of combustion, which have not
been discovered to consist of more than a single component
part. They are four in number; hydrogen, sulphur,
phosphorus, and carbon.
45. Hydrogen, as its name imports, is a principal constituent
part of water; for, singular as it may appear,
that well-known fluid is formed by a combination of two
species of air or gas, called hydrogen and oxygen (#21:n21#),
and in the proportion of about fifteen parts of the former
and eighty-five parts of the latter. This gas had
formerly the denomination of inflammable air, and has
long been known in mines under the name of fire-damp.
It is about twelve times lighter than atmospheric air.
When pure it soon destroys such animals, and extinguishes
all such flaming substances, as are immersed
in it. Mixed with atmospheric air, it explodes with
great violence on the application of any ignited body.
46. Sulphur is a simple combustible substance, of
yellow colour, which is found pure, or native, in several
parts of the world, and is sufficiently familiar to us
under the name of brimstone (#211:n211#). It strongly attracts
oxygen (#21:n21#), and is thereby converted into sulphuric
acid (#24:n24#). It frequently occurs in combination with
mineral substances, such as arsenic, antimony, copper,
and other metallic ores.
47. Phosphorus is a combustible substance which,
when pure, somewhat resembles bees’-wax both in colour
and consistence; and, when exposed to the air
under the usual temperature of our atmosphere, is luminous
in the dark, and has a smell somewhat resembling
// 035.png
.pn +1
that of garlic. It is so combustible that, when
melted, it should be kept under water, as it cannot
be exposed to the air during this process without great
risk of catching fire. This substance is not known in a
native state; and the whole of what is used in philosophy
and commerce is obtained by different artificial processes.
In union with oxygen (#21:n21#) it becomes converted
into an acid, called phosphoric acid (#25:n25#), and, under
this form, in conjunction with lime, it constitutes the
bones of men and animals. The greater part of the
phosphorus of the shops is obtained from bones.
48. Carbon is a name given to the pure inflammable
part of charcoal. It is abundantly diffused throughout
nature, for it enters into the composition of several
minerals, and of all vegetable and animal bodies. The
purest form under which carbon is known to exist is in
the diamond (#50:n50#). It may, however, be obtained sufficiently
pure, for all common purposes, by burning a piece
of wood, covered with sand, in a vessel called a crucible.
In combination with oxygen (#21:n21#) it forms carbonic
acid (#26:n26#). Carbon is a chief component part of pit-coal
(#217:n217#), petroleum (#213:n213#), and other bituminous substances.
// 036.png
.pn +1
.sp 2
.pb
.sp 4
.h3
CLASS I.—STONES.
.h4
ORDER I.—EARTHY STONES.
.hr 10%
.nf c
I. HARD: those which scratch Glass.
.nf-
.hr 10%
49. OF GEMS IN GENERAL.
.dv class=font85
Gems, or precious stones, as they are frequently
called, are, for the most part, transparent, and have a
vitreous or glassy appearance. Their different colours
are occasioned by metallic oxides (#21:n21#) of various
kinds, with which they are impregnated. Some writers
have classed them by their colours, but this is a very
uncertain mode, as different gems have not unfrequently
the same colour; and, in many cases, the same gems
are of different colours. The usual distinction of gems
into Oriental and Occidental is also liable to error, as
the best gems, from whatever part of the world they
are brought, are always called Oriental. The most
estimable of all the kinds are the diamond (#50:n50#), ruby
(#54:n54#), emerald (#67:n67#), and sapphire (#53:n53#); and stones a
grain in weight, and equal in quality, are valued in the
following proportions, at 8l. per carat for diamonds, 4l.
for rubies, and 3l. for each of the others. The amethyst
(#79:n79#), topaz (#61:n61#), and aqua-marine (#61:n61#), are considered
of nearly equal value with each other; and the garnet
(#70:n70#) is the cheapest of precious stones.
// 037.png
.pn +1
The ancients engraved upon several kinds of gems;
but they appear to have been ignorant of the art of
cutting the diamond, the ruby, and the sapphire, which
were too hard for them to operate upon. The emerald
and the noble opal (#102:n102#) were too highly esteemed as
precious stones to have often found their way into the
hands of engravers. It has been asserted that the ancients
did not use the topaz for engraving; but there
is extant a beautiful intaglio, representing an Indian
Bacchus, which is said to be a topaz. The garnet was
often engraved upon: and there are many master-pieces
of the art in calcedony (#91:n91#) and carnelian (93.) Onyx
and sardonyx (#92:n92#) were employed for that species of
engraving in relief called cameos; and, in many instances,
it is pleasing to observe with what dexterity
the ancient artists availed themselves of the different
colours in the alternate zones to express the different
parts and shades of their figures.
Most of the gems may be imitated by artificial preparations
of glass, coloured by different metallic substances;
and it is not easy, by mere inspection, to distinguish
the better kinds of factitious stones from real
gems. They are, however, discoverable by a deficiency
of lustre, and being so soft as, even in the most perfect
kinds, to yield to the point of a steel instrument.
The cutting and polishing of gems is the work of the
lapidary, and is in general thus performed:—The shape
most proper to be given to any particular gem being
determined on, the stone is cemented to the end of a
stick, and the different facets are formed by a mill
contrived for the purpose. This mill is a plate of copper,
or an alloy of lead and tin, to which an horizontal
motion is given by very simple machinery, and the surface
of which is charged either with diamond powder
and oil, or with fine emery and water. A thick peg of
wood called a gauge, pierced with small holes in all
directions, is set upright on the lapidary’s bench, close
to the mill, and the process of shaping the facets thus
takes place. The stone is placed on the surface of the
// 038.png
.pn +1
mill, the opposite end of the stick to which it is cemented
being inserted in one of the holes of the gauge.
In this position it is kept steady by the workman, with
his right hand, whilst, with the other, he puts the mill
in motion. The skill of the lapidary depends on regulating
the velocity of the mill, and pressing with more
or less force on the stick, with an almost imperceptible
tendency to one or other direction in different stages of
the work, examining each facet at very short intervals,
in order to give as great precision as possible to its size
and form. This part of the business being completed,
the cutting mill is taken out, and replaced by one of
brass, on which the polishing is performed by means of
fine emery (#58:n58#), tripoli, and rotten stone (#119:n119#), exactly
in the same manner as is practised in the first stage of
the process for setting the facets.
.dv-
.sp 2
.h5
DIAMOND.
50. The DIAMOND, or ADAMANT of the ancients, is
the most valuable of gems, and the hardest of all known bodies;
when pure, it is perfectly transparent.
In a rough state, diamonds have usually either the form of
rounded pebbles, with a shining surface, or they are crystallized
in the shape of octohedrons, or double four-sided pyramids.
(#Pl. II, Fig. 5, 6:pl-2#.) Though for the most part colourless, they are
sometimes yellow, green, blue, blackish, or rose-coloured.
The best diamonds are brought from the East Indies.
The principal mines are those of Raolconda and Coulour,
in the province of Golconda; and that of Soumelpour,
or Goual, in Bengal. At Raolconda they are
found in the deep crevices of rocks. Persons, by
means of long iron rods, with hooks at the end, draw
out from these crevices the loose contents, and afterwards
wash them in tubs, for the purpose of discovering
the diamonds.
The first discovery of diamonds at Coulour was about
two centuries ago, by a countryman, who, on digging
his ground to sow millet, accidentally found one of
these stones of large size. From that period the whole
// 039.png
.pn +1
adjacent plain began to be searched to the depth of
from ten to fourteen feet; and the work was, at one
time, so extensively pursued, that nearly 6,000 persons
were employed in it. At Soumelpour the diamonds
are found amongst the sand and gravel of the river.
Diamonds are likewise found in the island of Borneo,
and in several parts of South America. The mode by
which they are obtained from one of the rivers of
Brazil has been described by Mr. Mawe. The current
is turned, and part of the bed of the river being laid
dry, the mud is taken up and washed, by negroes, in
places prepared for the purpose, through which a portion
only of the stream is allowed to flow. As soon as
all the earthy particles have been washed away, the
gravel-like matter that remains is raked together, the
stones are thrown out, and what diamonds happen to
be present are found amongst the refuse that is left.
To ascertain whether a stone, that has been found,
be really a diamond, the workmen have a mode of
placing it upon a hard substance, and striking it with
a hammer. If it either resists the blow or separate into
leaves, it must be a diamond; but, in the latter case,
the discovery is sometimes made at an immense expense,
as, by thus diminishing the size, its value must
also, of course, be greatly diminished.
Diamonds are generally exported from Madras in a
rough state; and in small parcels neatly sewed in muslin,
and sealed by the merchants who send them.
These, we are informed by Mr. Milburne in his valuable
work on oriental commerce, are, for the most
part, sold in Europe by the invoice, as it is called; that
is, without being opened: and he says that they are
always found to contain the value for which they were
sold in India.
Of all transparent substances, none for brilliancy
can be compared with the diamond. Its hardness is
such, that no steel instrument whatever can make any
impression upon it. Notwithstanding this, at a temperature
not so high as that which is required for the
// 040.png
.pn +1
melting of silver, it gradually dissipates and burns.
Diamonds have been shown to consist principally of
carbon or charcoal in a pure and crystallized state.
The ancients, ignorant of the art of cutting diamonds,
were contented to set them in a native state;
and for this purpose they preferred such stones as had
naturally a crystallized form. The four large diamonds
which ornament the clasp of the Imperial mantle of
Charlemagne, and which are still preserved in Paris,
are uncut stones of this description. The extreme
hardness of the diamond baffled all attempts to polish it
in such manner as to exhibit its peculiar beauty, until
the year 1456, when a young man of Bruges, whose
name was Berquin, endeavoured to polish two diamonds
by rubbing them against each other. Having succeeded
in this, he next constructed a wheel, on which,
by means of diamond powder, he was enabled to cut
and polish these gems in a manner beyond his greatest
expectation. Since this period the art of polishing
them has been greatly improved both by the Dutch and
British jewellers.
In the choosing and valuing of diamonds in a rough
state, attention is paid to their colour, their being free
from extraneous matter, and their shape. Those that
are most perfect are crystalline, and resemble a drop
of clear spring water, in the middle of which is to be
perceived a strong light, that plays with great spirit on
moving them about. When they have a yellowish or
greenish tinge they are considered to be bad. Many
diamonds have a kind of confused structure, which
lapidaries compare to knots formed in wood. These
are rejected, from the impossibility of polishing them
properly.
Mr. Mawe remarks that diamonds, when rubbed
together, have a peculiarly and scarcely to be described
grating sound, which is one of their most remarkable
characteristics. By this alone rough diamonds may be
accurately and expeditiously distinguished from every
other gem.
// 041.png
.pn +1
It is usual to cut diamonds into three principal forms,
called brilliant (#Pl. II, Fig. 7:pl-2#), rose
(#Fig. 8:pl-2#), and table diamonds
(#Fig. 9:pl-2#). Brilliants are, for the most part, cut from
such of the stones as have naturally a crystallized
shape, and rose diamonds from the flat varieties. The
former are so called from their great lustre, in consequence
of the facets on both sides being cut. These
are always set upon a black ground, whilst rose diamonds,
which are much thinner, are set upon a white
foil speckled with black, for the purpose of adding to
their lustre. Rose-cut diamonds are of course much
less estimable than brilliants; so much so indeed, that
of late many of them, brought from Holland, have
been re-cut into brilliants, notwithstanding the additional
expense, and the loss of size necessarily attendant
on this operation. The table diamond is the least
beautiful of any. This mode of cutting is only adopted
for such stones, or rather fragments, as, with a considerable
breadth, have only a very trifling depth. The
diamond-cutters of England are considered to be the
best in Europe, but their number is so small as to occasion
many stones to be sent to Holland to be cut.
The value of diamonds is ascertained by their weight
in carats; and this value increases, in a very high
ratio, according to their magnitude. For instance, a
diamond weighing one carat will be worth about 10l.
whilst another of five carats will be worth 150l. and of
ten carats 800l.[#] This rule, however, can only be
taken for diamonds of twenty carats and under. The
larger ones, in consequence of the scarcity of purchasers,
are generally disposed of at prices greatly
inferior to their estimated worth. The value of some
diamonds that are peculiarly perfect exceeds the above
// 042.png
.pn +1
ratio; whilst, for a stone that is cloudy, foul, or of bad
colour, even three quarters of the estimated value will
perhaps be deducted.
.pm fn-start // A
A Carat is equal to four jeweller’s grains, seven grains of
which are equal to six grains troy. To ascertain the value of
wrought diamonds the weight must be doubled, about half being
supposed to be lost in the working. This sum must be multiplied
into itself, and the product by two. Thus to find the value of
a diamond of twenty carats 20 × 2 = 40 × 40 = 1600 × 2 = 3,200l.
.pm fn-end
No diamonds are so valuable as those that are perfectly
transparent, and of snow-white colour. The
green and yellow varieties are, however, much esteemed:
the blue kinds were formerly more valued than at present;
and the least valuable are those that have a grey
or brownish tint. Black diamonds are much prized
by collectors.
The principal use of the diamond is in jewellery. It
is also used by lapidaries, for slitting hard stones, and
for cutting and engraving upon other gems; by clock-makers
in the finer kinds of clock-work; in the glass-trade
for squaring large pieces or plates of glass, and
among glaziers for cutting their glass.
The largest diamond ever known (if it be such, and
not a white topaz, as some people have imagined) is
in the possession of the Queen of Portugal, and weighs
1,680 carats, or more than eleven ounces. It was found
in Brazil, and sent to Lisbon in the year 1746. It is
still uncut, and has been valued at 5,644,800l.
The Rajah of Mattan, in the island of Borneo, possesses
a large diamond, shaped like an egg, with an
indented hollow near the smaller end. It was found in
that island about eighty years ago, is said to be of the
finest water, and to weigh 367 carats, or more than two
ounces and a quarter. Several years ago the Governor
of Batavia, desirous of purchasing this gem, sent a
Mr. Stuvart to the Rajah, authorizing him to offer for
it 150,000 dollars, two large brigs of war, with their
guns and ammunition, together with a certain number
of great guns, and a quantity of powder and shot.
The Rajah, however, refused to deprive his family of
so valuable an hereditary possession; for the Malays not
only attach to it the miraculous power of curing all
diseases by means of water in which it is dipped, but
also believe that the fortune of the family is sustained
by its continuing in their possession.
// 043.png
.pn +1
Tavernier, the French Traveller, saw in the possession
of the Great Mogul a diamond which weighed near
280 carats. In form and size it resembled half a hen’s
egg. This diamond had been obtained from the mine
of Coulour, about the year 1550; and was valued at
more than 700,000l. sterling.
The sceptre of the Emperor of Russia is adorned
with an oriental diamond about the size of a pigeon’s
egg, which weighs 195 carats. This diamond is said to
have once been placed as the eye of an idol in Seringham,
in the Carnatic. A grenadier, who had deserted
from the French service in India, contrived to become
one of the priests of the idol, in the hope of being able
to steal this eye. He at length effected his purpose, and
escaped with the diamond to Madras, where he sold it
to the captain of a ship for a sum equal to 2,500l. of
British money. It was afterwards transferred to a Jew
for 18,000l. Coming into the hands of a Greek merchant,
he offered it for sale at Amsterdam, in 1766; and
the Russian Prince Orloff bought it for the Empress
Catharine for about 90,000l. sterling, and an annuity of
4,000l. during the life of the person who sold it.
The Pitt, or Regent diamond (#Pl. II, Fig. 10:pl-2#), which lately
was set in the handle of the sword of state of Buonaparte,
and is now possessed by the king of France,
is a brilliant of the most beautiful kind, and weighs
136¾ carats. It was brought from India by Thomas
Pitt, Esq. Governor of Fort George. Mr. Pitt has
himself stated, respecting it, that, in December, 1701,
whilst resident in Madras, several valuable stones, in a
rough state, were brought to him for sale by an eminent
diamond merchant. One of these, the diamond here
spoken of, was so large that the merchant asked for it
the sum of 85,000l. After much bargaining, Mr. Pitt
purchased it for 20,400l. He afterwards sold it for
135,000l. to the Regent Duke of Orleans; and by
him it was placed among the crown jewels of France.
The Pigot diamond weighs forty-seven and a half
carats. This, which is an extremely fine stone, was
// 044.png
.pn +1
disposed of by lottery, in 1800, for 22,000l.; and is
now in the possession of Messrs. Rundell and Bridge,
jewellers in London.
A large star, cross, and chain, worn on grand gala
days by the Prince of Brazil, as Sovereign of the different
Portuguese orders of knighthood, are each ornamented
with a great number of magnificent diamonds,
set in gold. The centre diamond of the star is alone
valued at 800,000l.
When the diamond is rubbed it will attract bits of
straw, feathers, hairs, and other small objects; and if
exposed to the rays of the sun, and immediately taken
into a dark place, some diamonds will appear luminous.
.sp 2
.h5
ZIRCON FAMILY.
.dv class=font85
51. JARGOON is a gem usually of smoky yellow or
brownish colour, and sometimes limpid: if placed upon any
object, it exhibits of it a very distinct double image.
The primitive form of its crystal is an octohedron (#Pl. II, Fig. 5:pl-2#),
but it is frequently crystallized in right-angled prisms, terminated
by four-sided pyramids.
.dv-
In hardness this stone does not much exceed that
of the emerald. The greyish white and yellowish
white varieties of jargoon are valuable chiefly on account
of their resemblance to the diamond. The darker-coloured
varieties can be deprived of their colour by
heat; and, in this state, though in lustre they are
infinitely inferior to them, they are sometimes substituted
for diamonds. Jargoons are now seldom used
except for the jewelling of watches and time-pieces.
About a century ago, they were much used in
mourning ornaments, for which the dark tone of their
colour, and their almost adamantine lustre, were supposed
to be peculiarly appropriate.
The jargoon is principally brought from the island
of Ceylon; but it is occasionally found in France, and
Spain, and in granite rocks near Cuffel, in Dumfrieshire,
Scotland.
// 045.png
.pn +1
52. The Hyacinth, or
Jacinth, is a dark orange-red
variety of jargoon. It is also chiefly imported from
Ceylon, where it is generally found in the sand of
rivers, in irregularly round pieces, but seldom of large
size without flaws.
This stone is indebted for its name to a supposed resemblance
in colour to that flower, which, according to
the Pagan mythology, Apollo raised from the blood of
his favourite youth, Hyacinthus.
When bright, and free from flaws, the hyacinth is a
superb ring stone; but it is not of usual occurrence in
modern jewellery.
.sp 2
.h5
RUBY FAMILY.
53. The ORIENTAL SAPPHIRE is a gem of blue colour,
the shades of which vary from a full and deep tint to a
nearly colourless appearance, and sometimes it is party-coloured.
It is found crystallized in six-sided pyramids much lengthened
and joined base to base (#Pl. II, Fig. 13:pl-2#); and also in rounded
or pebble-shaped fragments. It has a foliated texture, is
extremely hard, and about four times as heavy as water.
We are chiefly indebted for the sapphire to the East
Indies and the Island of Ceylon, where it is found
amongst the sand of the rivers. When brought into
Europe, it is cut by means of diamond powder, and
polished with emery. It is now usually set with a foil
of its own colour; but it was formerly the practice, instead
of foil, to place under this stone the blue part of
a peacock’s feather.
In hardness the sapphire ranks next to the ruby (#54:n54#);
and in value it is about equal to the emerald (#67:n67#). A
good sapphire of ten carats’ weight is worth about fifty
guineas. In the Museum of Natural History at Paris
there is a sapphire which weighs upwards of sixty-six
carats: it was placed there from the wardrobe of the
crown.
We are informed by M. Hauy that sapphires are
found in Bohemia and France, particularly in one part
// 046.png
.pn +1
of the Ville du Puy, among the sand of a rivulet near
Expailly. In the summer-time, when the rivulet is
nearly dry, they are collected by persons, each of whom
is furnished with a small tray and a linen bag. Where-ever
there are small depressions in which the water has
been stationary, these persons enter them, and fill their
trays with the sand. This they wash in water in such
manner that the lighter particles are carried away;
whilst the heavier ones of gravel, sapphire, and other
articles, remain at the bottom.
Some sapphires exhibit a kind of opalescence, or
whitish floating light in their interior. Sapphires lose
all their colour in the fire; and, after having been subjected
to heat, they are so hard and transparent as
sometimes to be sold for diamonds.
54. ORIENTAL RUBY is a precious stone of intense and
bright red colour, occasionally varied with blue, and sometimes
party-coloured.
In the general form of its crystals it much resembles the
sapphire (#53:n53#).
The ruby is imported into this country from the East
Indies, though seldom in a rough state, as the stones
are almost always first cut by the Indians for the purpose
of ascertaining their value. They are said to be found
in the sand of certain streams near the town of Sirian,
the capital of Pegu; and with sapphires in the sand
of rivers in Ceylon. But they are so seldom seen of
large size, that a ruby above thirty-one carats’ weight,
of perfect colour, and without flaws, is even more estimable
than a diamond of equal weight. The ruby is
usually set with a foil; but, if peculiarly fine, it is
sometimes set without bottom, that the stone may be
seen through.
Tavernier, the Eastern traveller, states that, in the
throne of the Great Mogul, he saw 108 rubies, which,
on an average, weighed from 100 to 200 carats each.
Among the jewels of the King of Candy, that were
sold by auction in London, on the 13th of June, 1820,
// 047.png
.pn +1
was a ruby which measured two inches in length, and
one inch in breadth. It was, however, interesting only
as a specimen for a cabinet, for it had, in various directions,
a great number of small hair-like tubes running
through it.
The hardness of this stone is such that the ancients
do not appear to have possessed the art of cutting it;
and, in the improvements which of late have been made
by Mr. Earnshaw in the construction of time-keepers,
no stones have been found sufficiently hard for jewelling
the holes, except the ruby and the diamond.
There are several modes of counterfeiting rubies;
and some persons have succeeded so well in imitating
these stones, that even the most able lapidaries, till they
try the hardness, may be deceived.
55. The Oriental Amethyst is an extremely rare
gem, usually of purple colour, apparently formed by an
union of the colouring matter of the sapphire and the
ruby. This stone, if heated, loses its colour, and becomes
transparent. After this process its brilliancy is
such that it is scarcely distinguishable from the diamond;
and, in jeweller’s work, it is occasionally substituted
for that gem. The common amethyst (#79:n79#), or
that which is chiefly seen, is nothing more than a violet-coloured
rock crystal (#78:n78#).
56. The Oriental Topaz and
Emerald are each varieties of the oriental ruby, the
former straw-coloured and the latter green. This kind of emerald
is imported from Pegu, and some other parts of the East Indies, and is
an extremely rare gem.
57. The SPINEL and BALAIS RUBY are two kinds of
precious stones, which differ from each other principally in colour,
the former being of a carmine, and the latter a cochineal red.
They vary from the oriental ruby (#54:n54#) in being less hard;
in the primitive form of their crystals being regular octohedrons
(#Pl. II, Fig. 5:pl-2#), and in their not being much more than 3
times heavier than water.
// 048.png
.pn +1
Although these two kinds of rubies are inferior, both
in lustre and colour, to the oriental ruby; yet, when
they exceed a certain size, they are much esteemed.
A spinel that weighs more than four carats is valued
at half as much as a diamond of the same weight, and
is not unfrequently imposed upon ignorant purchasers
for the oriental species. It is easily wrought, takes a
high polish, and is certainly a beautiful gem. Being
too expensive for necklaces, it is usually set in rings
and brooches, surrounded by brilliants.
The spinel ruby is found amongst sand, in one of
the rivers of Ceylon, which flows from the high mountains,
towards the middle of the island. It is also found
in Brazil; and in Hungary, Bohemia, and Silesia.
The Balais ruby is so named from Balacchan, the
Indian appellation of Pegu, from which country it is
chiefly imported.
58. EMERY is a very hard opaque mineral, of blackish or
bluish grey colour, which is chiefly found in shapeless masses,
and mixed with other minerals. It is about four times as
heavy as water.
The best emery is brought from the Levant, and
chiefly from Naxos, and other islands of the Grecian
Archipelago, where it occurs abundantly, in large,
loose masses, at the foot of primitive mountains. It is
also found in some parts of Spain; and is obtained
from a few of the iron mines in our own country.
In hardness it is nearly equal to adamantine spar;
and this property has rendered it an object of great
request in various arts. It is employed by lapidaries
in the cutting and polishing of precious stones; by opticians,
in smoothing the surface of the finer kinds of
glass, preparatory to their being polished; by cutlers,
and other manufacturers of iron and steel instruments;
by masons, in the polishing of marble: and, in their
respective businesses, by locksmiths, glaziers, and numerous
other artisans.
For all these purposes it is pulverized in large iron
// 049.png
.pn +1
mortars, or in steel mills; and is afterwards separated,
according to the several degrees of fineness that are required,
by washing it in water, and suffering the grosser
particles to deposit themselves. By this operation the
finer particles, which remain suspended in the water,
and which are obtained by decanting the water off, and
suffering it to stand for a considerable time, are separated.
The particles first deposited are again ground,
and again agitated in the water, to separate the finest.
By these successive operations the emery is reduced to
a powder so fine that, when rubbed between the fingers,
it communicates no sensation whatever of grittiness.
In general those particles only of the emery
which remain suspended in the water, after it has stood
about half an hour, are used to polish metals.
59. ADAMANTINE SPAR, or IMPERFECT CORUNDUM,
is a very hard and nearly opaque stone, which
varies much in colour, but is chiefly grey, with a greenish,
brown, or bluish tint.
It is usually found in the form of six-sided prisms, but it
sometimes occurs in shapeless masses, has a foliated texture,
and is about four times as heavy as water.
The name of adamantine spar was given, by the
British lapidaries, to this substance from its hardness
being nearly equal to that of the diamond. It was
originally discovered among the granite rocks of China;
but it has since been found, and in greater purity, in
Bengal and Ceylon.
In a powdered state this substance has long been
used by the artists of India and China for the cutting
and polishing of precious stones, and even of the diamond;
but, though it will in some degree operate upon
that gem, it is not sufficiently hard to bring out the
peculiar beauty of it in a degree at all comparable to
that which is effected by the European lapidaries with
diamond powder. The Chinese also use adamantine
spar for polishing steel, and in the composition of the
finer kinds of porcelain or earthenware. For the cutting
// 050.png
.pn +1
of seals and precious stones European workmen consider
it preferable to emery; but, for minute engraving,
it is much inferior to diamond powder.
60. CHRYSOBERYL is a gem of yellowish or brownish
green colour, harder than quartz (#76:n76#), and sometimes transparent;
but often only semi-transparent, in which case it exhibits
a bluish light, floating in the interior of the stone.
It is usually found in rounded pieces, but is sometimes crystallized
in compressed six-sided prisms, and in double six-sided
pyramids.
So little is this gem in request in Europe, that it is
seldom to be found in the possession of jewellers; but
in Brazil it is considered inferior only to the diamond.
It is usually procured from South America; yet it occurs
in Saxony; and, with the ruby and sapphire,
amongst sand in the rivers of Ceylon.
Such is the hardness of the chrysoberyl, that, when
properly polished, which is a difficult operation, it is
capable of receiving a lustre nearly equal to that of the
diamond. We are informed that, a few years ago, a
considerable number of these gems were imported into
this country from Brazil, but that the greater part of
them were entirely spoiled by inferior workmen, and
that the rest were so ill-cut that they remained unnoticed,
and without value. The smaller stones are said
to appear to most advantage in circular ear-drops; and
the larger specimens form necklaces and ring stones of
great beauty.
The variety which exhibits an opalescent appearance,
or presents a bluish light, undulating as it were in the
interior of the stone, and changing its situation according
to the position of the observer, is chiefly valuable
as an article of curiosity: the transparent kind is
always preferred by the jeweller.
.sp 2
.h5
SCHORL FAMILY.
61. The TOPAZ is a gem usually of a wine-yellow colour,
but sometimes orange, pink, blue, and even colourless, like rock
// 051.png
.pn +1
crystal; of a lamellar or foliated structure, harder than
quartz, but not so hard as ruby.
It varies considerably in its crystallization; is 3½ times
heavier than water; and, when placed upon any object, shows
a double image of it.
The name of topaz is derived from an island in the
Red Sea, where the ancients found a stone, but very
different from ours, which they denominated topaz.
The best topazes are of a deep colour, and are imported
from Brazil; the most brilliant ones are supposed to
be those of Saxony; but the latter are generally of
very pale colour. This species of gem is found in many
parts of Europe, but defective in transparency, and
sometimes even opaque. It occurs in large crystals, and
rolled masses, in an alluvial soil (#269:n269#), in the upper parts
of Aberdeenshire, Scotland; and in veins, along with
tin-stone, at St. Anne’s, in Cornwall. Topazes, more
than a pound in weight, have been found in Scotland.
Mr. Mawe speaks of a topaz mine at Capon, near
Villa Rica, in Brazil. In two breaks or slips of the
rocks, he says, there were little soft places where the
negroes found the topazes by scraping in them with
pieces of iron. He himself observed at least a cart-load
of inferior topazes, any number of which he might
have taken away; but all that he saw were defective
and full of flaws.
These stones vary much in size; some, particularly
those of Siberia, being extremely small, and others
being upwards of an inch in thickness. In the Collection
of Natural History at Paris there is a Brazilian
topaz which weighs four ounces and a quarter. These
stones are not sufficiently scarce to be, in general, much
valued by the jeweller or lapidary. The deep yellow
variety is preferred to the pale sort, although the latter
is often superior to it both in size and hardness.
Figures have sometimes been engraved on the topaz;
and these, when well executed, are of great value. In
the National Museum at Paris there is a superb Indian
Bacchus engraven on a topaz. The cabinet of the Emperor
// 052.png
.pn +1
of Russia contains several fine topazes of this
description.
Some of the coarse kinds of topaz are broken down,
pounded, and used instead of emery for the cutting of
hard minerals; and powdered topaz was formerly kept
in apothecaries’ shops, and sold as an antidote against
madness.
It is a somewhat singular circumstance, that, if the
Saxon topaz be gradually exposed to a strong heat in a
crucible, it will become white and, on the contrary,
that Brazilian topazes by the same process become red
or pink. By exposure to a still stronger heat, the Brazilian
topaz changes its colour to a violet-blue.
Jewellers usually divide topazes into the following
kinds:
62. Brazilian and Saxon, already mentioned.
63. Bohemian.—These are found chiefly in the tin
mines of Bohemia, are of small size, deficient in transparency,
have only grey or muddy white colours, and
are of little value.
64. Blue Topaz.—This is a large Brazilian gem,
which varies in size from one or two carats to two or
three ounces. A fine blue topaz, without flaw, and
which weighed an ounce and a quarter, was sold for
200 guineas. It is sometimes difficult to distinguish a
blue topaz from an aqua marine (#68:n68#).
65. Pink Topaz.—Some beautiful rose-coloured
varieties of topaz have been brought from Asia Minor,
and others are found in South America; but the pink
topazes in the jewellers’ shops are chiefly stones of the
yellow Brazilian kind, which have had their colour
changed by heat.
66. The White, or Nova Mina Topaz, is a perfectly
colourless and transparent variety. It generally
occurs of small size, and is in considerable estimation in
Brazil for ear-rings, or for being set round yellow topazes.
// 053.png
.pn +1
Small stones of this description have recently
been found at St. Michael’s Mount, in Cornwall.
There is imported from Brazil a yellow kind of
crystal (#83:n83#), which is so similar, in its appearance, to
the yellow topaz as sometimes to be imposed upon purchasers
for that stone.
67. The EMERALD is a well-known gem, of pure green
colour, and somewhat harder than quartz.
Its natural form is a short six-sided prism; but it is sometimes
found massive, and rounded like a pebble.
By the ancients the emerald was a gem much in request,
and particularly for engraving upon. They denominated
it smaragdus, and are said to have procured
it from Ethiopia and Egypt; but, besides the true
emerald, Pliny, under this title, includes green jasper
(#96:n96#), malachite (#231:n231#), fluor spar (#194:n194#), and some other
green minerals. The pillars of emerald in the temple of
Hercules at Tyre, mentioned by Herodotus, and the
large emeralds described by Pliny as having been cut
into columns and statues, cannot be referred to the true
emerald.
The deepest coloured and most valuable emeralds that
we are acquainted with are brought from Peru. They
are found in clefts and veins of granite, and other primitive
rocks; sometimes grouped with the crystals of
quartz (#76:n76#), felspar (#110:n110#), and mica (#123:n123#); and, not unfrequently,
loose in the sand of rivers. The most ancient
emerald mine is that of Manta, in Peru, but it has
been some time exhausted; and most of the emeralds
that are now brought to Europe are obtained from a
mine situated in the valley of Tunca, between the
mountains of New Grenada and Popayan.
The emerald is one of the softest of the precious
stones; and is almost exclusively indebted for its value
to its charming colour. The brilliant purple of the
ruby, the golden yellow of the topaz, the celestial blue
of the sapphire, are all pleasing tints; but the green of
the emerald is so lovely, that the eye, after glancing
// 054.png
.pn +1
over all the others, finds delight in resting upon this.
In value it is rated next to the ruby; and, when of good
colour, is set without foil and upon a black ground,
like a brilliant diamond. Emeralds of inferior lustre are
generally set upon a green gold foil. These gems appear
to greatest advantage when table cut (#Pl. II, Fig. 9:pl-2#), and
surrounded by brilliants, the lustre of which forms an
agreeable contrast with the quiet hue of the emerald.
They are sometimes formed into pear-shaped ear-drops;
but the most valuable stones are generally set in rings.
A favourite mode of setting emeralds among the opulent
inhabitants of South America is to make them up
into clusters of artificial flowers on gold stems.
The largest emerald that has been mentioned is one
said to have been possessed by the inhabitants of the
valley of Manta, in Peru, at the time when the Spaniards
first arrived there. It is recorded to have been
as big as an ostrich’s egg, and to have been worshipped
by the Peruvians, under the name of the Goddess, or
Mother of Emeralds. They brought smaller ones as
offerings to it, which the priests distinguished by the
appellation of daughters. Many fine emeralds are
stated to have formerly been bequeathed to different
monasteries on the Continent; but most of them are
said to have been sold by the monks, and to have had
their place supplied by coloured glass imitations. These
stones are seldom seen of large size, and at the same
time entirely free from flaws.
The emerald, if heated to a certain degree, assumes
a blue colour; but it recovers its proper tint when cold.
When the heat is carried much beyond this, it melts
into an opaque coloured mass.
The precious stone called oriental emerald (#56:n56#) is a
green and very scarce variety of the oriental ruby.
68. The BERYL, or AQUA MARINE, is a light or
mountain green variety of the emerald, sometimes straw-coloured,
bluish, yellow, or even white.
These stones are of such frequent occurrence, even
// 055.png
.pn +1
in large pieces perfectly clear and free from flaws, they
are in general so soft, and have so little the brilliancy of
other gems, that they are usually considered of inferior
value. The most beautiful kinds are brought from
Dauria, on the frontiers of China, from Siberia, and
from Brazil. They are also found in Saxony and the
South of France, and are very common at Baltimore, in
North America. Specimens of aqua marine have been
obtained from the upper parts of Aberdeenshire, Scotland,
where they sometimes occur in alluvial soil, along
with rock crystal and topaz. These stones have also
been found, embedded in granite, near Lough Bray,
and Cronebane, in the County of Wicklow, Ireland;
and also in mountain rock, in some parts of Devonshire.
They are cut by means of emery (#58:n58#), and polished
with tripoli (#119:n119#). The darkest green specimens are
set upon a somewhat steel-coloured foil; and the pale
ones are either placed, like the diamond, on a black
ground, or upon a silvery foil. The aqua marine is
usually made into necklaces; but it is likewise employed
for brooches, and not unfrequently for steel stones and
intaglios. The larger ones are in much esteem among
the Turks for the handles of stilettos.
69. The TOURMALINE is a stone belonging to the same
family as the emerald, and generally of a smoky blackish colour:
sometimes, however, it is green, red, blue, or brown;
and, when not very thick, it is transparent.
It is occasionally found in shapeless masses, but more frequently
crystallized in three, six, or nine-sided prisms, variously
truncated or terminated; and its weight is somewhat
more than three times that of water.
This stone was first made known in Europe, about
the beginning of the last century, by the Dutch merchants,
who brought it from the island of Ceylon, where
it is principally found. When strongly heated it becomes
electric; one of the summits of the crystal negatively,
and the other positively. An early writer, by
whom it is mentioned, says, that “it has the property
// 056.png
.pn +1
not only of attracting ashes from the warm or burning
coals, but that it also repels them again, which is very
amusing: for as soon as a small quantity of ashes leaps
upon it, and appears as if endeavouring to writhe themselves
by force into the stone, they in a little time
spring from it again, as if about to make a new attempt.
It was on this account that the Dutch called it the
ashes drawer.”
Since the above period, tourmaline has been found
in Brazil; and in Norway, Germany, France, and several
other parts of Europe. It generally occurs embedded
in different kinds of mountain rock; and, in
these, is rather confined to single beds or strata, than
disseminated through the whole mass of the mountain.
A piece of tourmaline, of cylindrical form, and brownish
grey colour, was some time ago discovered in the
neighbourhood of Kitt-hill, near Callington, Cornwall.
Black tourmaline, both in large and small crystals, is
found in granite rock, in the vicinity of the Logan, or
Rocking-stones, near Treryn, in the same county.
When laid on a table, the tourmaline appears a dark
and opaque stone; but, when held against the light, it
has generally a pale brownish hue. It is sometimes cut,
polished, and worn as a gem; but, on account of the
muddiness of its colours, it is not in general much
esteemed. Those persons who wear tourmalines set in
rings consider them more as objects of curiosity than of
elegance: they show them as small electrical instruments,
which, after being heated a little while by the
fire, will attract and repel light bodies.
In the superb collection of minerals of the British
Museum, there is a magnificent specimen of red
tourmaline, or rubellite, which has been valued at
1000l. sterling. It was presented by the King of Ava
to the late Colonel Symes, when on an embassy to that
country, and was afterwards deposited by the latter in
Mr. Greville’s collection; with that collection it became
the property of the British Museum.
// 057.png
.pn +1
.sp 2
.h5
GARNET FAMILY.
70. The PRECIOUS, or NOBLE GARNET, is a gem
of crimson colour, which, when crystallized, has the form of a
twelve-sided solid (#Pl II, Fig. 11, 12:pl-2#). It is sufficiently hard to
scratch quartz, and is about four times as heavy as water.
This stone is found abundantly in many mountains
(particularly of primitive rock), in different parts of the
world. But garnets of the hardest and best quality are
brought from Bohemia, where there are regular mines
of them; and a great number of persons are there employed
in collecting, cutting, and boring them. The
boring is performed by an instrument having a diamond
at its extremity, which is rapidly turned by a bow.
The work is so expeditiously performed, that an expert
artist can bore 150 garnets, or he can cut and polish
thirty, in a day. In Suabia there are two towns in
which upwards of 140 persons are employed in these
operations.
In general garnets are stones of inferior value.
When compared with the ruby, those even of finest
quality have a very sombre appearance. The kinds
most esteemed are such as have a clear and intense red
colour, or a rich violet or purplish tinge. The best
garnets are cut in the manner of other precious stones,
and are usually set upon a foil of the same colour. To
heighten the colour and transparency of certain garnets,
jewellers either form them into what are called
doublets, by attaching to the lower part of the stone a
thin plate of silver, or they hollow them underneath.
Crystals of garnet sometimes occur three or four
inches in diameter. These are cut into small vases;
which, if of good colour, and free from defects, are
highly valued. Many fine engravings have been
executed on garnet. One of the most beautiful that is
known is a figure of the dog Sirius, in the possession of
Lord Duncannon.
The coarser kinds of garnet are used as emery for
// 058.png
.pn +1
the polishing of other minerals; and are thus prepared.
They are made red-hot, then quenched in water, reduced
to powder in an iron mortar, and lastly diffused
through water, poured into other vessels, and allowed
to settle, in order to obtain an uniform powder. This
powder is known to artists by the name of red emery.
It has been conjectured that our garnet was the
same kind of stone which, on account of its colour, the
ancients denominated carbuncle.
71. Common Garnet.—A very inferior variety of
garnet, of brown or greenish brown colour, is found
in our own country, and particularly amongst rocks
near Huntley, in Aberdeenshire, Scotland. These garnets,
however, are, in general, so soft as to be of little
value to the lapidary; and consequently are seldom cut
or polished for ornamental purposes. But being easily
fused, and abounding in iron, they are occasionally employed
as a flux in the smelting of rich iron ores: and as
an addition to poor ones.
72. Syrian Garnets are distinguished by their violet
or purplish tinge. Some writers state that they have
their name from the word Soranus, which signifies a
red stone; and others from Sirian, a town in Pegu,
where they are said to be found in great beauty.
73. Pyrop Garnets are of a dark blood-red colour,
which, when the stones are held between the eye and
the light, falls strongly into yellow: they are chiefly
brought from Bohemia: are employed in almost every
kind of jewellery, and generally set with a gold foil. At
Waldkirch, in Suabia, there are twenty-four mills for
the cutting and polishing of pyrop garnets: and 140
masters are occupied in manufacturing these stones.
74. Vesuvian is a liver-brown kind of garnet, that
was originally found among rocks ejected from Mount
Vesuvius; and in the vicinity of which mountain it
still occurs in considerable abundance. At Naples it
// 059.png
.pn +1
is cut into stones for rings and other ornaments. Vesuvian
has of late years been found in other parts of
Europe; and even at Kilranelagh, and Donegal, in
Ireland.
75. Cinnamon Stone is a kind of garnet of hyacinth-red
colour, which is found in angular and roundish
pieces among the sand of rivers in the island of Ceylon.
It is cut as a precious stone; and, when of good colour,
and free from flaws, is of considerable value.
.sp 2
.h5
QUARTZ FAMILY.
76. COMMON QUARTZ is a hard and foliated substance,
usually of white or grey colour, and more or less transparent.
It is generally found in shapeless masses, which are nearly
thrice as heavy as water, and the fracture of which is glassy.
When crystallized, it most commonly has the form of a six-sided
prism, terminated by a pyramid of six sides.
This kind of stone forms a constituent part of many
mountains, and is very common in our own, as well as
in most other countries. It is sufficiently hard to scratch
iron and steel; and it has the property, after having
been several times successively made red-hot, and dipped
into water, of communicating to that fluid a certain
degree of acidity.
Quartz is employed, in place of sand, for making the
finer kinds of glass; and also in the manufacture of
porcelain. For the latter purpose great quantities are
collected from the mountains of Wales, ground into
powder, and in that state shipped to Liverpool, and
other parts. After having been burnt and reduced to
powder, it is sometimes mixed with clay, and formed
into bricks for the construction of glass furnaces: these
are capable of resisting the intense heat which is requisite
in the fusion of glass.
77. Burrstone is a vesicular and corroded variety
of quartz, which forms a most excellent and valuable
// 060.png
.pn +1
kind of millstone. It is chiefly found in France; but
is so much esteemed by the English millers, that the
Society of Arts, in London, for many successive years,
offered a considerable reward for its discovery in Great
Britain. At length a vein of burrstone was discovered
in the Moel y Golfa hills, North Wales, by a
Mr. Evans, who, in consequence received a premium
from the Society. About the same time another
vein was opened near Conway; and the same Society,
in 1800, gave a premium of 100l. to the widow and
orphan children of the discoverer. Both these quarries
were sufficiently convenient for water carriage; yet the
demand for the Cambrian burr did not answer the expectation,
and millstones of French production were
still preferred to them.
The mode of splitting these stones, as it is practised
in some parts of France, is singular, and affords a proof
of the extraordinary power of capillary attraction. The
blocks are first cut into the form of cylinders, sometimes
many feet in height. To split these horizontally
into millstones, circular indentations are made
round them, at proper distances, according to the
thickness that is to be given to the stones; wedges of
willow, that have been dried in an oven, are then
driven into the indentations with a mallet. When these
have been sunk to a proper depth, they are moistened
with water; and, after a few hours, the several stones
that have been marked out are found to be perfectly
separated.
78. ROCK CRYSTAL is an extremely beautiful kind of
quartz, sometimes perfectly transparent, and sometimes shaded
with grey, yellow, green, brown, or red. It occurs in the
form of crystals with six sides, each terminated by a six-sided
prism.
The name of this substance was considered by the
ancients to signify ice, or water crystallized; and they
imagined that crystal was produced from a congelation
of water.
// 061.png
.pn +1
Its uses are numerous. It is cut into vases, lustres,
and snuff-boxes; and many kinds of toys of extremely
beautiful appearance are made of it. When pure and
perfectly transparent, it is much in request by opticians,
who make of it those glasses for spectacles which are
called pebbles, and who use it for various kinds of optical
instruments. The best crystal is imported from
Brazil and Madagascar, in blocks, not unfrequently
from fifty to a hundred pounds in weight.
This stone is wrought into the different shapes that
are required, by sawing, splitting, and grinding. The
sawing is effected by an extended copper wire fixed to
a bow: the wire is coated with a mixture of oil and
emery, and is drawn backward and forward until the
operation is performed. But, as this process is a
tedious one, particularly when the mass is large, a more
expeditious, although less certain, method is sometimes
adopted. The crystal is heated red hot, and a wet
cord is drawn across, in the direction that the workman
intends to split it. By the rapid cooling thus effected, in
the direction of the cord, the stone easily splits by a single
blow of the hammer, and generally in the direction
required. The grinding is performed by means of emery:
and the polishing effected by tin ashes and tripoli.
The ancients held vases that were made of this stone
in great estimation, particularly when they were of
large size. Of two cups which the tyrant Nero broke
into pieces in a fit of despair, when informed of the
revolt that caused his destruction, one was estimated to
be worth more than 600l. of our money. The most valuable
kind of crystal that was known to the ancients was
obtained from the island of Cyprus; but it was often
faulty in particular parts, having flaws, cracks, and
blemishes. When the crystal was used for the engraving
of intaglios and cameos, the artist could sometimes
conceal these defects amongst the strokes of his work;
but, when it was to be formed into cups or vases, this
could not be done, and for the latter purpose the purest
pieces only could be employed.
// 062.png
.pn +1
In the counties of Cornwall and Derby, in the neighbourhood
of Bristol, and amongst the mountains of
North Wales, small crystals of this kind are frequently
found: these are respectively called Cornish, Buxton,
Bristol, and Snowdon diamonds. We are informed that
the crevices of some parts of Mont Blanc and the Alps
contain rock crystal in such abundance as to be perfectly
bristled with it.
Some crystals contain in their substance drops of
water, or other kind of fluid; and these, as curiosities,
are usually sold at a rate considerably higher than
others. There are in the British Museum specimens
of crystal which enclose many kinds of foreign substances,
such as ironstone, needle antimony, and asbestos
(#136:n136#).
Various means have been devised for communicating
colours to rock crystal. If it be heated and plunged
into a solution of indigo, or copper, it acquires a blue
colour; or if into a decoction of cochineal, a red colour.
A clove-brown colour may be given by exposing it to
the vapour of burning wood. Artists sometimes communicate
beautiful colours to rock crystals, by forming
them into what are called doublets. Two modes of
doing this are adopted. In one, a stone that is brilliant-cut
at the top is hollowed underneath, filled with
the colour that the stone is intended to exhibit, and
then closed at the bottom by a plate of glass. If this
kind of doublet be dexterously executed, the deception
is not easily discovered; for the whole mass will appear
of an uniform tint. The second kind of doublet is
formed by cementing a coloured plate of glass on the
base of a rose or brilliant-cut crystal: by this the whole
stone acquires the colour of the plate.
There are found in nature, many coloured kinds of
crystal. These are often confounded with precious
stones; and, as such, are made into female ornaments
of different kinds. The following are the principal of
them.
// 063.png
.pn +1
79. Common Amethyst.—This is a violet-coloured
crystal, which acquires considerable brilliancy in polishing,
and is sometimes of sufficient size to be formed
into columns more than a foot in height, and several
inches in diameter. When the colour is good, and
uniformly diffused, amethysts are cut into necklaces,
bracelets, ear-rings, and seals; and, when less pure, they
are manufactured into snuff-boxes. They are valued
in proportion to the depth of their colour, and to their
perfect transparency. The most favourite form in
which they are made up is in necklaces; and as it is
not easy to find a number of perfect stones with precisely
the same tint of colour, necklaces of this description
are very valuable. The finest that is known was
in the possession of her late Majesty. When the colour
is not uniformly diffused, jewellers sometimes expose
amethysts, for a little while, in a mixture of sand and
iron-filings, to a moderate heat; and, by this process,
their appearance is rendered more uniform.
The amethyst being almost the only coloured stone
that can be worn with mourning, it derives, from this
circumstance, a considerable addition of value.
This species of gem was well known to the ancient
Greeks and Romans, and was held by them in great
esteem. Its name is derived from the Greek language,
and implies a power of preventing intoxication; which
(originating no doubt in the resemblance of its colour
to that of wine, and the absurd doctrine of sympathies)
it was believed by the ancients to possess. They
ascribed to it many other virtues, equally surprising and
equally absurd; particularly that the wearing of it
would expel melancholy, procure the confidence and
friendship of princes, render people happy, and even
dispel storms of wind and hail. The ancients frequently
engraved upon amethyst; and their favourite
subject was the representation of Bacchus and his followers.
The most valuable amethysts are imported into
// 064.png
.pn +1
Europe from India and Ceylon. These, although they
are with truth denominated oriental, must be carefully
distinguished from the true oriental amethyst (#55:n55#),
which is a much more valuable gem. The amethysts
next in esteem are found in Brazil, and are procured
in the mining districts of that country. Siberia, and
various countries in Europe, especially Germany and
Spain, also furnish very beautiful amethysts; and inferior
stones of this description are even found in the
mountainous districts of some parts both of Scotland
and Ireland.
80. False Ruby is a crystal of red colour, and found
in Bohemia, Silesia, and Barbary.
81. False, or Water Sapphire is a blue crystal,
which does not differ much in appearance from the
true sapphire, but is considerably less hard. This
kind is found in Bohemia, Silesia, and some parts of
Switzerland, but it is not so valuable as the last.
82. False Emerald is a green variety of crystal, the
scarcest and most valuable of all the coloured kinds.
It is chiefly found in Saxony and Dauphiny.
83. Yellow, or Topazine Crystal is a stone of
wine-yellow colour. It is found in Brazil and Bohemia,
but has no other alliance with the true topaz than its
colour.
84. Cairn Gorum Crystals are obtained in various
parts of Scotland, but particularly from a mountain
of that name in the county of Aberdeen. They are
usually of smoky yellow or brown colour, and are, at this
time, so much in request for ornamental articles of
dress, that several lapidaries have been induced to settle
in Aberdeen, who are constantly employed in cutting
them for seals, rings, necklaces, brooches, and other
trinkets. When these crystals are of deep and good
colour, they are nearly as estimable as topazes; and,
if clear and large, they are sold at a high rate. The
// 065.png
.pn +1
price of inferior seal-stones varies from ten shillings to
three or four pounds each; but those of superior beauty
will produce from five to ten guineas. Such specimens
as have a pure and full yellow colour are often sold
for topazes. When they are muddy, the lapidaries have
the art of entirely dissipating the colour, and giving
them a transparent lustre. This is done by means of
heat, which will dissipate the colour of every species
of crystal.
85. AVANTURINE is a quartz, generally of reddish
colour, sprinkled with yellowish shining points of mica (#123:n123#),
which are dispersed through its whole substance.
A French artist, some years ago, having by accident,
or “par aventure,” suffered a quantity of brass filings
to fall into a vessel of melted glass, afterwards found
that it was admirably calculated for vases and different
kinds of ornamental work. Hence he denominated it
avanturine, a name which mineralogists have since applied
to those natural objects of which this production
of art was an apparent imitation.
Avanturine is found in some of the countries bordering
upon the White Sea, in Spain, and some parts of
France. In the late Leverian Museum there was a
piece which weighed near five pounds, and was unique
both for beauty and magnitude. It had been discovered
in 1788, amongst the ruins of the triumphal arch
of Julius Cæsar in the valley of Suse, in Piedmont; and
was purchased of the person who found it for 200
guineas. Avanturine is cut into various ornamental
articles, which are sometimes sold at a very high
price.
Imitations of it are very common, and are formed by
the simple operation of throwing brass or copper filings
into coloured glass in a state of fusion.
86. CATS-EYE is a stone of brownish grey colour, tinged
with green, yellow, white, or red; semi-transparent, and reflecting
from its interior a splendid white line or speck, which
// 066.png
.pn +1
varies according to the direction in which the stone is held to
the light.
It is found in pieces that are rounded, massive, or blunt-edged.
These stones are considered by some writers as varieties
of quartz (#76:n76#), and by others as a kind of opal
(#102:n102#). They are sometimes found in Hanover, but
are chiefly brought from the island of Ceylon. It is
usual to cut them before they are exported, and generally
in a convex and oblong form, without facets,
and in such manner as to bring the streak which intersects
them into the centre. Among the king of Candy’s
jewels, which were sold by auction in London, in June
1820, was a cat’s-eye of extraordinary magnitude and
beauty. It was two inches in diameter, of dark colour,
and nearly hemispherical. This stone was set in gold,
with small rubies round it, and was sold for more than
400l.
Cat’s-eyes are chiefly used for setting in rings.
Their size seldom exceeds that of a hazel nut; but
there was one in the cabinet of the Dukes of Tuscany,
which was nearly an inch in diameter. Those that are
the most highly esteemed are of an olive-green, or red
colour.
87. WOODSTONE is a very hard mineral substance,
supposed to have been wood petrified with a siliceous mineral
called hornstone.
It is of various colours; and has not only the external appearance,
but the internal organization of wood.
This extraordinary mineral is found embedded in
sandy loam, in alluvial soil (#269:n269#), and occurs in various
parts both of Europe and Asia. It has been found in
ferruginous sand, near Woburn, in Bedfordshire, and
near Nutfield, in Surrey. Immense pieces of it are
discovered in some places in the original shape of the
trees; trunks, branches, and roots. In the year 1752
the whole under part of the trunk of a tree, with its
branches and roots, was found, in a state of woodstone,
// 067.png
.pn +1
near Chemnitz, in Saxony; and, in the Electoral Cabinet
at Dresden, there is part of the trunk of a tree,
from the same place, which measures five feet in length
and as many in thickness.
Woodstone is in considerable request by lapidaries.
It takes a good polish, and is made into beads for necklaces,
and other female ornaments. In the East Indies
it is generally called Petrified Tamarind Tree.
88. COMMON SAND is a granulated kind of quartz;
or consists of rounded grains of small size, which have a vitreous
or glassy surface.
It is usually of white or yellowish colour; but is sometimes
blue, violet, or black.
In the torrid regions of Africa and Asia there are
immense tracts of desert covered only with sand, so
dry and light as to be moveable before the wind, and
to be formed into vast hills and boundless plains. These
are incessantly changing their place, and frequently
overwhelm and destroy the travellers whose necessities
require them to enter these dreary realms.
Sand has numerous uses. When mixed in due proportion
with lime, it forms that hard and valuable cement
called mortar. Melted with soda (#200:n200#) and
potash (#205:n205#) it is formed into glass; white sand being
used for the finer kinds, and coarse and more impure
sand for bottle glass. A very pure kind of sand
which is found in Alum Bay, on the west side of
the Isle of Wight, and on some parts of the coasts of
Norfolk, is in great request by glass-makers. Sand is
also employed in the manufacture of earthenware; and
its utility in various branches of domestic economy,
but particularly for the scouring and cleaning of kitchen
utensils, is well known. In agriculture sand is used
by way of manure, to all soils of clayey lands: as it
renders the soil more loose and open than it would
otherwise be. The best sand for this purpose is that
which is washed by rains from roads or hills, or that
which is taken from the beds of rivers.
// 068.png
.pn +1
There is a kind of sand which is naturally mixed
with clay, and has the name of Founder’s Sand, from
its being chiefly employed in the formation of moulds
to cast metals in. At Neuilly, in France, there is a
bed of perfectly transparent and crystalline sand.
Each grain, when examined with a magnifying glass,
is seen to consist of a perfect six-sided prism, terminated
by two six-sided pyramids.
The uses of the different kinds of Sandstone will be
enumerated in the account of the rocks (267, 268).
89. LYDIAN STONE is a kind of flinty-slate, of greyish
or velvet-black colour, not quite so hard as flint, opaque, and
about twice and a half as heavy as water.
It is usually massive, and, internally, has a glimmering
appearance.
This mineral occurs in beds in primitive clay-slate
(#257:n257#); and is found in Bohemia and Saxony, and also
in the Pentland hills near Edinburgh. It was first
noticed in Lydia, whence it derived its name.
It is sometimes used as a touchstone to ascertain the
purity of gold and silver. This was its use among the
ancients. The metal to be examined is drawn along
the stone so as to leave a mark, and its purity is judged
by the colour of the metallic streak. A good touchstone
should be harder than the metals, or metallic
compounds to be examined; if softer, the powder of
the stone mixes with the trace of the metal and obscures
it. A certain degree of roughness on the surface
of the best stone is also requisite, that the metal to
be tried may leave a trace or streak sufficiently distinct.
It must not, however, be too rough, otherwise the particles
of the metal will be hid amongst its inequalities,
and no distinct trace will be formed. The touchstone
should also be of black colour, as this tint shows the
colour of the streak better than any other.
90. FLINT is a peculiarly hard and compact kind of stone,
generally of smoke-grey colour, passing into greyish white,
// 069.png
.pn +1
reddish, or brown. It is nearly thrice as heavy as water, and
when broken will split, in every direction, into pieces which
have a smooth surface.
It is very common in several parts of England, generally
among chalk, arranged in a kind of strata or beds, and in
pieces that are for the most part either rounded or tubercular.
The property which flint possesses of yielding sparks,
when struck against steel, has rendered it an article of
indispensable utility in the system of modern warfare.
To this substance the sportsman also is indebted for
a means of obtaining his game. The art of cutting,
or rather of breaking, this stone into gun-flints is of
modern date, and was for a long time kept secret.
The most absurd and contradictory accounts have been
given of it by various writers; and it is only of late
that the true mode has been rendered public. It consists
in striking the stone repeatedly with a kind of
mallet, and bringing off at each stroke a splinter which
is sharp at one end and thick at the other. These
splinters are afterwards shaped, by placing them upon
a sharp iron instrument, and then giving them repeatedly
small blows with a mallet. During the whole
operation the workman holds the stone in his hand,
or merely supports it on his knee: and the operation
is so simple, that a good workman has no difficulty
in making 1500 flints in a day. The manufacture
of gun-flints is chiefly confined to England, and two
or three departments in France. In Prussia an attempt
was once made to substitute a kind of earthenware or
porcelain for flint; and such was, for some time, used
by the Prussian soldiers. All the kinds of flint are
not equally adapted for guns: the best are the yellowish
grey; the dark smoke and ash-grey varieties are
also used, but they are neither so easy to be split, nor
do they afford such thin fragments as the other; and,
owing to their greater hardness, they wear the lock
sooner.
Flint is employed in the manufacture of porcelain
and glass. For this purpose it is heated red hot, and, in
// 070.png
.pn +1
that state, is thrown into cold water. It is then of a
white colour, and capable, without difficulty, of being
reduced to powder, either in a mortar or by a mill.
After this powder has been passed through fine sieves,
some aqua fortis is poured upon it, to dissolve any
particles of iron which it may have acquired in the
grinding. The powder is then several times washed in
hot water, and afterwards dried for use. The glass that
is manufactured from this substance is perfectly transparent
and faultless.
Glass is made by mixing sand, or prepared flint, with
a certain proportion of soda (#200:n200#) or potash (#205:n205#); and
exposing these substances, in a furnace, to a violent
heat. When they are in a perfectly fluid state, part of
the melted matter is taken out at the end of a long
hollow tube. This is done by dipping the tube into it,
and turning it about until a sufficient quantity is taken
up; the workman, at each turn, rolling it gently upon
a piece of iron, to unite it more intimately. He then
blows through the tube till the melted mass, at the extremity,
swells like a bubble; after which he rolls it
again on a smooth surface to polish it, and repeats the
blowing until the glass is brought as nearly to the size
and form of the vessel required, as he thinks necessary.
If he be forming a common bottle, the melted matter
at the end of the tube is put into a mould of the exact
size and shape of the body of a bottle; and the neck is
formed by drawing out the ductile glass at the upper
extremity.
If he be making a vessel with a large or wide orifice,
the glass, in its melted state, is opened and widened
with an iron tool; after which, being again heated, it
is whirled about with a circular motion, and, by the
centrifugal force thus produced, is extended to the size
required. Should a handle, foot, or any thing of similar
kind be required, that is made separately, and stuck on
in its melted state.
Window glass is made in a similar manner, except
that the mass at the end of a tube is formed into a
// 071.png
.pn +1
cylindrical shape. This being cut longitudinally by
scissars or shears, is gradually bent back until it becomes
a flat plate.
Large plate glass for looking-glasses is made by suffering
the mass, in a state of complete fusion, to flow
upon a casting table, with iron ledges. These confine
the melted matter, and, as it cools, a metallic
roller is passed over it, to reduce it to an uniform
thickness.
Glass utensils, unless very small and thin, require to
be gradually cooled in an oven. This operation is
called annealing, and is necessary in order to prevent
them from cracking by change of temperature, wiping,
or slight accidental scratches.
It appears that the manufacture of glass was known
very early; but glass perfectly transparent was esteemed
of extremely high value. It is stated that the Emperor
Nero purchased two glass cups with handles for a sum
which was equivalent to 50,000l. of our money. The
windows of some of the houses of the ancient city of
Pompeii, which was buried by an eruption of Mount
Vesuvius, in the year 79, were glazed, but the glass
was thick, and not transparent.
By many persons flint is used as a test for ascertaining
the purity of silver coins. This is done by
rubbing them upon the flint; and if the mark which
they leave be not perfectly white, they are rejected as
counterfeit.
91. CALCEDONY is a species of quartz, generally of
whitish, bluish, or smoke-grey colour; and, when broken, it
appears internally dull, and somewhat splintery.
It is generally found in a massive state, is harder than flint,
generally semi-transparent, and 2½ times heavier than water.
The name of this stone is derived from Chalcedon,
in Upper Asia, whence it appears to have been originally
obtained, and where it is still found in considerable
abundance. Several superb specimens of calcedony
have been found in Britain, and particularly in
// 072.png
.pn +1
some of the tin and copper mines of Cornwall. It
occurs in several parts of Scotland; and in many of the
countries of the Continent. In the Leverian Museum
there was a specimen of calcedony, which weighed
more than 200 pounds. Its whole surface appeared such
that, at first sight, one might imagine it to have formerly
been in a liquid state: it had much the appearance
that thick oil has while boiling.
Few stones are susceptible of a higher or more
beautiful polish than calcedony. Hence the different
varieties of it are cut into ring and seal stones, necklaces,
ear-pendants, small vases, cups, and snuff-boxes.
92. ONYX is a kind of calcedony, generally marked alternately
with stripes of white and black, or white and brown.
Its name is derived from the Greek language, and
has been given on account of its resemblance in colour
to the whitish band at the base of the human
nail. The distinction which appears to be made
betwixt onyx and sardonyx, arises from the colours of
the former being arranged either concentrically, or in a
somewhat confused manner, and those of the latter in
regular stripes or bands.
Both these kinds are highly esteemed by lapidaries,
for the formation of vases, snuff boxes, and trinkets
of various kinds. Of sardonyx the ancients made
those beautiful cameos, many of which still ornament
our cabinets. The ingenuity they have shown, in the
accommodation of the natural veins and marks of the
stone to the figures engraven upon them, is such as to
excite, in many instances, the greatest admiration.
It is said that we are entirely ignorant of the country
whence the ancient artists obtained the large specimens
of sardonyx which are now found in some cabinets.
Onyx is imported from the East Indies, Siberia,
Germany, and Portugal.
93. CARNELIAN is another kind of calcedony usually
of a red or flesh colour, though sometimes white, orange, or
yellow.
// 073.png
.pn +1
On several of the British shores carnelians are found
with other pebbles: but the most beautiful and valuable
kinds are imported from the East Indies. These are
sometimes so large as to measure nearly three inches
in diameter. The kinds principally in request are those
of pure white, and bright red colour; and jewellers
have the art of changing the colour of the yellow
varieties to red, by heat.
No stone is so much in request for seals as carnelian.
It is likewise cut into beads for necklaces, and stones
for ear-rings; into crosses, bracelets, and other trinkets,
which, in India, form a considerable branch of traffic.
The amount of the sale value of different kinds of carnelian
goods vended by the East India Company in
1807, was 11,187l.: but, in other years, it has not
usually been so much as half that sum.
Formerly carnelians were exported from Japan to
Holland; and thence were carried to Oberstein, in
France, to be exchanged for the agates of that country,
which were exported to China.
The carnelian was much esteemed by the ancients;
and many fine engraved carnelians are preserved in different
collections.
94. CHRYSOPRASE, an extremely hard kind of stone,
of clear and delicate apple-green colour, is considered to be a
kind of calcedony.
This beautiful mineral has hitherto been found
only in the vicinity of Kosemitz, and in a few
other parts of Lower Silesia. It is susceptible of
a high polish, and is much prized by jewellers when
its colour is deep and pure. Its colour, however,
is so fugitive, that, if kept in a warm and dry situation,
it loses the greatest part of it; and if exposed to
moisture it becomes much altered. Lapidaries assert,
that great care ought to be taken in the polishing
of it;—pretending that if, from want of sufficient
moisture, or by the too rapid motion of the wheel,
it be over-heated, it will become whitish or turbid.
// 074.png
.pn +1
Chrysoprase is generally cut into a convex form, or
what jewellers call en cabochon; and is set with green
taffeta beneath it, as foil. It is used for ring stones,
brooches, and other ornaments; and is found to harmonize
well with diamonds and pearls. The larger and
more impure masses are cut into snuff-boxes, seal
stones, and similar articles. Some of the finest specimens
of chrysoprase that are known, are to be seen in
the cathedral church of Prague, where a small closet is
inlaid with them.
Imitations of chrysoprase are sometimes imposed
upon the public; but these are easily known by persons
who are acquainted with the nature of precious stones.
95. BLOODSTONE, or HELIOTROPE, is an opaque
stone of the quartz family, generally of dark green colour,
with a somewhat bluish cast, and marked with blood-red spots
or stripes.
It usually occurs in masses of irregular form; and, when
cut thin, is sometimes translucent at the edges.
The most valuable kinds of bloodstone are imported
from the East. They are not so opaque as those which
are found in Germany, and are marked with more vivid
spots. As bloodstone is capable of a high polish, and
is even better calculated for engraving upon than carnelian
(#93:n93#), it is in great request for seal stones, for the
tops and bottoms of snuff-boxes, and other articles
on which costly gold mountings are frequently bestowed.
Its dark colour and opaque appearance prevent
its being much used for beads. Great quantities of it
are consumed in China as ornaments to the girdle clasps
of the superior ranks of people. Absurd as it may appear,
many persons entertain a notion that this stone
worn in the dress will prevent bleeding at the nose.
Good bloodstone and carnelian are considered to be
about the same value.
There are many cameos and intaglios, both by ancients
and moderns, executed in bloodstone. In the
National Library at Paris, there is a fine engraved stone
of this kind, representing the head of Christ whilst undergoing
// 075.png
.pn +1
the punishment of scourging, and so cut that
the red spots are made to represent drops of blood.
The ancients procured bloodstones chiefly from
Ethiopia; but, at present, the most highly esteemed
varieties are brought from Bucharia, Great Tartary,
and Siberia. A kind of mineral nearly resembling this
is found in Rum, one of the western isles of Scotland.
The spots in bloodstone are particles of red jasper.
96. JASPER is a species of quartz, and one of the hardest
stones with which we are acquainted. It varies much in colour,
being red, green, yellow, blue, olive, violet, black, and
often variegated, spotted, or veined with several other colours.
It is usually opaque, but is capable of receiving a beautiful
polish.
This stone is found in large and shapeless masses, and constitutes
an ingredient in mountains of various parts of the
world.
Such is the hardness of jasper, that the savages of
Canada avail themselves of it for the fabrication of the
heads of javelins, and sometimes also of arrows. It is
used by artists for the formation of vases, snuff-boxes,
seals, and trinkets of various kinds; and formerly cups
and saucers were sometimes made of it. Many beautiful
antique engravings have been made upon jasper.
In the province of Andalusia, in Spain, there are
four fine quarries of jasper. One of these is celebrated
for a blood-red stone, streaked with white, exceedingly
hard and very handsome, of which the beautiful columns
of the tabernacle in the Escurial are made. This quarry
is in the territory of Cogullus, in the archbishopric
of Seville, and was purchased by the Crown in 1581;
but was afterwards so far neglected that even the place
where it lay was not remembered. It was, however,
again discovered about the end of the reign of Charles
the Third, after a very expensive search made by order
of the government.
Jasper occurs in the Pentland hills, near Edinburgh,
and in several other parts of Scotland; in the Shetland
Islands, and Hebrides. It has been observed in most of
// 076.png
.pn +1
the countries of the Continent; and is found, in great
abundance, in Siberia.
97. Red Jasper is an opaque red stone which is found
embedded in red clay-ironstone in Baden; and is cut and
polished for various ornamental purposes. There are
extant many fine antique engravings on red jasper.
98. Egyptian Pebble is a kind of jasper, that is
found in globular or rounded pieces, and is distinguishable
when cut or broken, by its numerous colours, arranged
in concentric stripes or layers. It is chiefly brought
from Egypt; and, as it is capable of receiving a fine
polish, and when polished is very beautiful, it is manufactured
into several kinds of ornamental articles.
From the great abundance in which it is supplied, it is,
however, much less valuable than carnelian (#93:n93#). The
colours of the Egyptian pebble frequently assume very
singular forms. There was one in the Leverian Museum
which exhibited, in the centre, the resemblance of a
pantaloon, or a man wearing a fool’s cap.
99. Striped, or Ribbon Jasper, is marked with alternate
stripes of different colours; and is found in
Siberia, Saxony, and even in the Pentland hills, near
Edinburgh. It receives an excellent polish, and is frequently
cut into the tops and bottoms of snuff-boxes.
The red and green layers of jasper, being well defined
and regular, this kind is used for several purposes of
ornament, particularly for cameos.
100. AGATE, or AGATE JASPER, as some mineralogists
denominate it, is a semi-transparent stone of the quartz family,
which is capable of receiving a high and very beautiful polish.
These stones are always found in a shapeless or massive
form, and nearly of all colours, except bright red and green.
The name of agate is derived from the river Achates,
in Sicily, in the vicinity of which these stones were
obtained by the ancients in great abundance. They are
now found in several parts of Scotland; in Iceland,
Saxony, and Hungary; and they are occasionally
brought into Europe from China and the East Indies.
// 077.png
.pn +1
Agates are used in several kinds of ornamental work,
and particularly for necklaces and seals. They are
occasionally made into cups, the handles of knives and
forks, hilts of swords and hangers, and the tops and
bottoms of snuff-boxes. The less ornamental kinds are
manufactured into small mortars, which are employed
by enamellers and others, for pounding such substances
as are too hard to be reduced in any other way. They
are also made into instruments for grinding colours,
and into polishers for the glazing of linen. In the
Electoral Cabinet at Dresden, and the Ducal Cabinet
in Brunswick, there are several elegant vases formed of
agate.
The most beautiful agates which our island produces
are known by the name of Scots Pebbles. These are
found in various parts of Scotland, but principally on
the sea-shore, in the neighbourhood of Dunbar. Agate
pebbles are found on several of the English shores, as
those of Suffolk, Dorset, Scotland, Wales, and Ireland;
and sometimes even in gravel pits. Many of them will
bear cutting and polishing as well as the best agates of
foreign countries.
Agates are occasionally seen to be figured in very
singular manner; but this, in some instances at least, is
suspected to be the work of art. One is mentioned in
the church of St. Mark, at Venice, which had the representation
of a king’s head surmounted by a diadem.
On another, was represented a man in the attitude of
running. But the most remarkable of all seems
to have been one which contained a representation of
the nine Muses, with Apollo in the midst of them!
It must be remarked that agate is not, as some mineralogists
imagine, a simple mineral, but that it is composed
of various species of the quartz family, intimately
blended together. It consists chiefly of calcedony (#91:n91#),
with flint, hornstone, carnelian (#93:n93#), jasper (#96:n96#), cacholong
(#105:n105#), amethyst (#79:n79#), and quartz (#76:n76#). Of these
minerals sometimes only two, and sometimes three or
more, occur in the same agate. Its varieties, consequently,
are extremely numerous.
// 078.png
.pn +1
101. Mochoa Stone is a kind of agate, which has on
its surface the resemblance of moss; and this so nearly
approaching a natural appearance, that some persons
have actually supposed it to be occasioned by a condensation
of moss into stone. Its name is derived from
mocks, the German word for moss.
These stones are used for several ornamental purposes;
and are not unfrequently imitated, by spreading
a solution of copper in nitric acid or aqua fortis (#30:n30#)
over the surface of a plain agate, and then setting a
small iron nail on its head in the middle. The acid
unites with the iron, and deposits the copper in beautiful
ramifications from the centre. The nail must then be
removed, and the surface carefully washed by dipping
the stone into warm water. Afterwards, on the application
of a moderate heat, the copper becomes black.
As, however, the deposition is merely superficial, it requires
to be covered with glass, to preserve it from
injury.
102. OPALS are a semi-transparent kind of stones, which
have a milky cast, and, when held betwixt the eye and the
light, exhibit a changeable appearance of colour.
They are always found in a shapeless or massive state, are
brittle, and considerably less hard than most other precious
stones.
The only opal mines in the world are those of Hungary.
About four centuries ago, opals were obtained,
in such abundance, from these mines, that upwards
of three hundred persons were employed in them.
They still produce opals, some of which are so valuable
as to pass, in commerce, under the appellation of oriental
opals, whilst others are so poor as to be of no value
whatever to the jeweller. Opals are also found in other
parts of Europe; and in the island of Sumatra and
several parts of the East Indies.
Few precious stones are more beautiful than opals.
Their elegant play of colours, brilliant blue, green,
red, and yellow, variously modified, has procured for
// 079.png
.pn +1
them a distinguished rank among gems. Notwithstanding
this, they are but ill suited to the purposes
of jewellery, on account of their softness, their great
frangibility, and their sometimes splitting on a sudden
change of temperature. They are usually set without
bottoms; but sometimes with a black bottom, and
sometimes with a foil of red, blue, or gold colour.
Their value is such that a fine oriental opal is considered
worth about twice as much as an oriental sapphire of
the same size. By the Turks they are so peculiarly
esteemed, that a fine opal of moderate size has sometimes
been sold at the price of a diamond. The esteem
in which they were held among the ancient Romans was
such, that Nonius, the Roman senator, is stated to have
preferred banishment to parting with a favourite opal
which Mark Antony was anxious to possess.
In the abbey of St. Denys, near Paris, there was
formerly a curious ancient opal which was green on the
outside, and, when viewed against the light, exhibited
a fine ruby colour: and in the Imperial Cabinet at
Vienna, there are two pieces of opal, from the mines in
Hungary, one of which is about five inches long, and
2½ inches broad; and the other the size and shape of a
hen’s egg. Both these stones exhibit a very rich and
splendid play of colours.
In the purchasing of opals great caution is requisite,
as fine glass pastes have not unfrequently been substituted
for them, and sold at enormous prices.
103. Hydrophanous Opal, or Oculus Mundi, is
a kind of opal, the distinguishing characteristic of which
is, that it gradually becomes transparent, and exhibits a
beautiful play of colour after being immersed in water.
It is either of a whitish brown, yellowish green, milky
grey, or yellow colour, and opaque; and, when touched
by the tongue, adheres to it.
The name of oculus mundi has been given to these
stones from an internal luminous spot, which changes
// 080.png
.pn +1
its position according to the direction in which they are
held to the light. The countries in which they are
chiefly found are Hungary and Iceland.
They are sometimes set in rings; and the prices at
which they were formerly valued were, in the highest
degree, unaccountable and absurd. At present their
value is considerably lower, though they are still in
great request as objects of curiosity. The phenomenon
of their becoming transparent in water is supposed to
be occasioned by that fluid soaking through their whole
substance, in the same manner as the transparency of
paper is occasioned by immersing it in oil. An hydrophanous
opal weighing 27½ grains was kept four minutes
in water, and, on being taken out, weighed 32½ grains,
having received in this short period an augmentation
of five grains, or more than one sixth part of its whole
weight. When taken from the water, these stones as
they dry become again opaque.
To preserve them in beauty and perfection, care
should be taken not to immerse them in any but pure
water, and to take them out as soon as they have acquired
their full transparency. If these precautions be
neglected, the pores will soon become filled with earthy
particles: the stones will cease to exhibit their peculiar
property, and will ever afterwards continue
opaque.
104. Common Opal is a semi-transparent kind of
opal, which does not exhibit any changeable refraction of
colour. It is found in Germany, France, Italy, and
other countries of the Continent, and is employed for
brooches and other ornaments. A green-coloured
Saxon variety is sometimes cut into ring-stones.
105. Mother-of-Pearl Opal, or Cacholong,
is a milk-white, yellowish, or greyish-white kind of opal,
which occurs in Iceland, Greenland, Spain, and the
island of Elba. It is sometimes cut into a concave
form, for brooches, and other female ornaments. Italian
artists also use it for mosaic work.
// 081.png
.pn +1
106. Wood Opal appears to be wood that, by some
extraordinary operation of nature, has been converted
into opal. Some specimens exhibit, very beautifully,
the ligneous texture. This kind of opal is chiefly cut
into plates for the tops and bottoms of snuff-boxes. It
is found in alluvial land in some parts of Germany and
Hungary. Several years ago the trunk of a tree, penetrated
with opal, and so heavy that eight oxen were
requisite to draw it, was found in Hungary.
.sp 2
.h5
PITCHSTONE FAMILY.
107. OBSIDIAN is a kind of glass, generally of blackish
colour, formed in volcanoes, from which it issues in thick
streams.
This substance has been used for various purposes.
It is possible to cut and polish it; but its brittleness and
frangibility are so great, that, without much care, it will
fly into pieces during the working. The reflectors of
telescopes are sometimes formed of it. In Mexico and
Peru obsidian is cut into mirrors; and the inhabitants
of those countries used formerly to manufacture it into
knives and other cutting instruments. Hernandez says
that he saw more than a hundred of these knives made
in an hour. Cortez, in a letter to the Emperor Charles
the Fifth, relates that he saw razors that had been formed
of obsidian. The natives of Easter and Ascension Islands
use this substance for cutting instruments; and also for
pointing their lances and spears, and, in place of flint,
for striking fire with. According to the account that
has been given by Pliny, the ancients sometimes formed
obsidian into mirrors, and ornamental articles of different
kinds. The Danish lapidaries, who obtain considerable
quantities of it from Iceland, cut it into snuff-boxes,
ring-stones, and ear-pendants.
Obsidian is found near Mount Hecla, and in other
parts of Iceland. Sir George Mackenzie, during his
journey through that island, observed an immense mass
of this substance, which appeared to him to have been
// 082.png
.pn +1
part of a stream that had flowed from a volcano. It is
also found in Sicily, and several other islands of the
Mediterranean; and in nearly all parts of the world
where there are volcanoes.
108. PUMICE is an extremely light and porous mineral,
of somewhat fibrous texture, and of white, grey, reddish,
brown, or black colour.
From the texture of this mineral, which is chiefly
brought from the neighbourhood of volcanoes, some
persons have imagined it to be asbestos decomposed by
the action of fire. Its lightness is such that, placed in
water, it will float.
To mechanics and other artists pumice stone is a
very useful mineral. It is employed for cleansing and
smoothing the surface of wood, leather, metal, stones,
glass, and other substances; and it is used by parchment-makers,
curriers, and hat-makers. Hence it forms
a considerable article of trade: and is exported from
the Lipari Islands, in great quantities, to the different
countries of Europe. Sailors in the Mediterranean
rub their beards off with pumice, instead of shaving.
On account of its porosity, it is used in Teneriffe as a
filtering stone. It forms a pernicious ingredient in
some kinds of tooth powder; and in Italy is ground
and used instead of sand, in the making of mortar.
Pumice occurs in Ireland, along with obsidian (#107:n107#);
and it abounds in several islands of the Grecian
Archipelago.
.sp 2
.h5
AZURE STONE FAMILY.
109. LAPIS LAZULI, AZURE STONE, or LAZULITE,
is a mineral of azure-blue colour in various shades,
and generally accompanied with white or clouded spots, and
also with pyrites (#236:n236#), which have the appearance of golden
veins or spots. Its texture is earthy, and fracture uneven. It
is opaque, or nearly so, and, in some parts, is sufficiently hard
to strike fire with steel. We are not informed that lapis lazuli
is otherwise found than in shapeless masses or lumps.
// 083.png
.pn +1
About fifty years ago this stone was an article much
in fashion for various ornamental parts of dress. Being
capable of very high polish, it was cut into beads,
stones for rings, bracelets, and necklaces. It was also
cut into ornamental vases, small statues, and the tops
and bottoms of snuff-boxes; but of late it has been
almost wholly out of use for these purposes. Before
the French Revolution it was imported, to considerable
extent, into that country from the Persian Gulf
for the inlaying of richly-decorated altars; and its value
was appreciated according to the proportion of its yellow
spots or veins: these, by many persons, were erroneously
considered to be of gold.
The most important purpose to which lapis lazuli is
now applied is in the manufacturing of the beautiful
and brilliant blue colour so much esteemed by painters,
called ultramarine. For the making of this, such
pieces are selected as contain the greatest proportion
of blue substance, and consequently the least yellow or
white. These are burned or calcined, reduced to a fine
powder, made into a paste with wax, linseed oil, and
resinous matters of different kinds, and afterwards
separated by washing. The powder that is left in this
operation, which requires much time and great attention
to perform, is ultramarine.
There are few colours so little susceptible of change
from the effects of time as ultramarine: the consequence
of this has been that, as several of the ancient
painters introduced it for the representation of blue
drapery, their pictures, in many instances, are now devoid
of harmony, as this colour alone has stood, whilst
all the others have changed.
Lapis lazuli is principally brought from Persia,
Natolia, and China; but it is also found in Siberia and
Tartary. In Europe it has been discovered only in
Germany, and among the ruins of Rome.
A coarse imitation of it is sometimes made by throwing
copper filings into blue enamel whilst in a melted
state.
// 084.png
.pn +1
.sp 2
.h5
FELSPAR FAMILY.
110. COMMON FELSPAR is a hard kind of stone which
varies much in colour, being flesh-red, bluish grey, yellowish
white, milk-white, or brownish yellow.
It is found in a massive state, disseminated or crystallized in
four, six, and ten-sided prisms; will strike fire with steel, and
is sometimes opaque and coloured, sometimes transparent and
whitish.
The name of felspar is derived from the German
language, and signifies spar of the fields. It is a very
common substance, and constitutes a principal part of
many of the highest mountains of the world. When
exposed to weather, it gradually acquires an earthy
appearance, and at length passes into porcelain clay
(#118:n118#).
Felspar is of great use in the manufacture of the
finer kinds of earthenware. Of the two substances
which chiefly compose the porcelain of China, one
called petunzé is a whitish laminar kind of felspar.
This mineral is used in the celebrated porcelain that is
manufactured at Sevres, near Paris, for the purpose of
giving to it a white and transparent appearance. Previously
to being used, it is pulverized, made into a
paste, and suffered to dry. It is sometimes applied to
the surface of ornamental vases in the form of enamel.
111. Amazon Stone is a green variety of felspar,
which is found in small rolled pieces on the bank of
the river of Amazons, in South America, whence it has
its name. It is susceptible of a beautiful polish, and is
often cut into ring-stones, brooches, and the tops of
snuff-boxes. Lapidaries consider it to be most estimable
when accompanied by mica, which gives it a kind
of speckled perlaceous appearance.
112. LABRADOR FELSPAR is a very beautiful stone,
of smoky grey colour, intermingled with veins and shades of
blue, green, and golden yellow, exhibiting a brilliant play of
// 085.png
.pn +1
colours, according to the position with respect to the light in
which it is held.
The original discovery of this singular mineral was
by the Moravian missionaries, on the island of St.
Paul, near the coast of Labrador; but it has since been
found in various parts of Norway and Siberia. Persons
who have passed in boats along the rivers of Labrador,
have described the extremely brilliant and beautiful appearance
which the rocks of this substance frequently
exhibit in shallow places, at the bottom of the water.
The visitors of the late Leverian Museum will, no doubt,
recollect a remarkably fine mass of Labrador felspar,
the surface of which was polished, and exhibited some
of the most splendid and beautiful colours that can
be imagined. It was considered to have been the most
capital specimen that was ever brought to England.
This mineral, on account of its hardness, its brilliancy,
and its capability of receiving a high polish,
is in considerable estimation among lapidaries for different
kinds of ornamental work, particularly for the
tops and bottoms of snuff-boxes, for brooches, and
necklaces.
113. MOONSTONE, or ADULARIA, is the purest kind
of felspar that is known; and is considered to have the same
relation to common felspar that rock crystal has to common
quartz. Its colour is white, sometimes with a shade of yellow,
red, or green.
The translucent varieties of this stone, when viewed
in a certain direction, sometimes exhibit a pearly and
silvery play of colour. These are valued by jewellers,
who cut them into a semi-globular form, and sell them
under the name of moonstone. Those specimens are
considered most estimable which, when cut in a very
low oval, present the silvery spot in the centre of the
stone. They are generally used for rings and brooches;
and when set round with diamonds, their pearly lustre
exhibits a striking and agreeable contrast with the brilliancy
of that gem.
// 086.png
.pn +1
Adularia is said to have been first discovered by an
Italian mineralogist, near Mount St. Gothard, in Switzerland.
He named it Adularia felspar, in the belief
that the mountain on which he had found it was named
Adula. This, however, was not the case; for Mount
Adula is at some distance from St. Gothard, in the
Grisons. This mineral has since been found in the
granite of the island of Arran, in France, and Germany.
The finest specimens are brought from Ceylon.
.hr 10%
.sp 4
.h4
ORDER II.–SOFT STONES.
.nf c
(Those which will not scratch Glass.)
.nf-
.sp 1
.hr 10%
.sp 1
.h5
CLAY FAMILY.
114. Clay is a mixture of alumine (#33:n33#) and silex (#38:n38#), and is too
well known to require much description.
It is opaque, has an earthy texture, is about twice as heavy
as water, when moistened is very ductile, adheres slightly to
the tongue; and with its peculiar smell (called clayey) every
one is acquainted.
115. COMMON CLAY, or POTTER’s CLAY, which
is found in nearly every country of the world, is sometimes
white, has a blue or yellowish tinge, or is brown or reddish.
It is the peculiar quality of this substance to become
so hard by heat that it will even strike fire with steel.
The ductility of clay, and its property of thus hardening
in the fire, have rendered it an article of indispensable
utility to mankind in all civilized countries. It is
formed into eating vessels of almost every description;
plates, dishes, cups, basins, bowls, and pans for keeping
provisions in. For these almost any kind of clay may
be advantageously used; but it is necessary to mix it
with sand, for the purpose of rendering the vessels
// 087.png
.pn +1
that are made of it more firm and strong. Those that
are applied to culinary, and other uses in which it is
requisite for them not to be penetrable by water, are
covered with a glazing. This glazing, for coarse ware,
is sometimes made with lead, and sometimes by
throwing a certain portion of salt into the furnace. In
the formation of the better kinds of earthenware, the
clay is made into a paste with water, moulded into the
requisite shape upon an horizontal wheel, the inside
being formed by one hand of the potter, and the outside
by the other, as the wheel turns round. When
the pieces have been baked, they are dipped into a
glazing mixture, consisting of white lead, ground flints,
and water, and are exposed a second time to the fire.
The different colours of earthenware are obtained by
means of various kinds of metallic oxides (#21:n21#).
The coarser kinds of clay are manufactured into
bricks for the building of houses, and tiles for the covering
and paving of them. These are formed in
moulds of the requisite shape, afterwards dried for
some time in the sun, and finally piled in kilns, and
there baked to a proper degree of hardness. The earth
for bricks ought to be sufficiently fine, free from pebbles,
and not too sandy, which would render them
heavy and brittle; nor ought it to be entirely free from
sand, as this would make them crack in drying.
Clay is a substance of inestimable value for forming
the bottoms of ponds, and the bottoms and sides of
canals and reservoirs, to prevent the water from draining
away. It also composes, in a great measure, those
tenacious earths called arable soils. What is peculiarly
denominated clay land is known by its holding water,
and not soon drying when wetted. Such land requires
much labour from the husbandman, before it can be
sufficiently pulverized, or brought to a fit state for
being productive of corn or grass.
116. Pipe Clay is a fine and yellowish white variety
of common clay. It is very plastic, adheres strongly to
// 088.png
.pn +1
the tongue; and, in a strong heat, is hardened, and
rendered perfectly white.
It is of this clay that tobacco pipes are made, by
the simple process of casting them in moulds, forming
a hole through the stems by means of a wire, generally
dipping the small end into some glazing material, and
then baking them. Pipe clay is also formed into oblong
pieces, dried, and employed for cleaning white woollen
cloths, and for various purposes of domestic utility. It
is likewise the basis of the yellow, of what is called
Queen’s ware pottery. This is glazed in a manner
somewhat different from that of common pottery. The
glazing mixture consists of a certain proportion of carbonat
of lead (#239:n239#), ground flint, and flint glass, worked
with water to the thickness of cream. The ware, before
it is glazed, is baked, and thus acquires the property of
strongly imbibing moisture. It is then dipped into the
above composition; exposed a second time to the fire,
by which the glaze it has imbibed is melted. A thin
glossy coat is thus formed upon its surface, which is
more or less yellow, according to the greater or less
proportion of lead that has been used.
117. LOAM is a yellowish or brownish kind of clay; sometimes
containing a considerable proportion of sand. It occurs
in immense beds, and is found in almost every part of the
world.
This substance, when mixed with straw or hair, to
prevent it from cracking, is extensively used for the
building of what are called mud cottages or houses.
These are generally reared on a foundation of stone, or
brickwork, to secure them from injury by the moisture
of the earth. It is said to be the most advantageous
practice to form the loam into bricks, and to dry these
in the shade, and afterwards in the sun. The use of such
bricks is of great antiquity. We are informed that the
ancient city of Damascus, and even the walls of Babylon,
were constructed of bricks made of loam.
// 089.png
.pn +1
118. PORCELAIN CLAY is generally of white or reddish
white colour, sometimes inclining to yellowish or grey. When
dry, it absorbs moisture rapidly; and it becomes very tenacious
when kneaded.
It is known from the other clays by the fineness of its particles,
its soiling the fingers much when handled, and its fine
but meagre feel.
The usual distinction betwixt earthen ware and porcelain
is, that the former is opaque, and the latter semi-transparent.
In the manufacture of porcelain the clay
is sometimes used alone, and sometimes intermixed
with other earths, or with felspar (#110:n110#). The earliest
manufacture of porcelain is supposed to have been that
in China and Japan. The quantity produced in China
must formerly have been extremely great; as not only
a considerable portion of the eastern parts of the world,
but almost the whole of Europe, was supplied with it.
In a single province it is said that nearly a million of
persons were at one time employed in this manufacture.
The manufactory at Sevres, in France, has long been
celebrated both for the excellence and elegance of its
porcelain. There are well-known manufactories of porcelain
at Meissen in Saxony, at Berlin, and in Austria;
but none of these are at present superior to our own, in
Worcestershire and Staffordshire.
Porcelain clay occurs chiefly in countries which
abound with granite (#251:n251#) and gneiss (#255:n255#). It is found
in small quantity in Cornwall, and other granite districts
of England, as well as in those of Scotland and Ireland.
But the most valuable kinds of this clay are found in
China and Japan.
The mineral is not used in the state in which it is
found in the earth; but is previously washed several
times to free it from impurities. After the process
of washing, only about fifteen parts of pure clay remain:
this is the kaolin of the Chinese. To form the
composition of the porcelain, this clay is mixed, in certain
proportions, with quartz (#76:n76#), flint, gypsum (#192:n192#),
// 090.png
.pn +1
steatite (#124:n124#), or other substances; and the mixture is
sifted several times through hair sieves. It is afterwards
moistened with rain water, and, in the form of a paste,
is put into covered casks. Here a fermentation soon
takes place, which changes its smell, colour, and consistence.
Its colour passes from white into dark grey;
and the matter becomes both tougher and more soft
than before. The peculiar mode of preparing this mixture,
and the art of rightly managing it, are secrets in
most porcelain manufactories.
The next operation consists in giving to the paste
thus formed the requisite shape of the vessels. This
is done first by kneading it with the hands; and then
by taking up certain portions of it, and turning it on a
lathe, in the manner of common pottery (#115:n115#), but with
more care.
The third operation is the baking or firing. This is
done in furnaces of a particular construction, and generally
lasts from thirty-six to forty-eight hours. The
state of the baking is shown by proof pieces, as they
are called, which are placed in convenient situations,
and can be drawn out, from time to time, for examination.
The porcelain in this state, is named biscuit porcelain;
and figures, and such other porcelain articles as
are neither to be painted nor exposed to water are in
the state of biscuit.
A fourth operation is covering the surface of the biscuit
with a varnish or enamel. This is composed of
pure white quartz (#76:n76#), white porcelain, and calcined
crystals of gypsum (#192:n192#); and sometimes principally
of felspar (#110:n110#). These substances are carefully ground,
then diffused through water, and formed into a paste.
When used, the paste is diluted in water, so as to give
it considerable fluidity; and the pieces of biscuit porcelain
are separately plunged into it, in such manner as
to cover their whole surface. These are then exposed
to a heat sufficient to melt the enamel or covering: and
in this state they constitute white porcelain.
If the porcelain is to be painted, it must again be
// 091.png
.pn +1
exposed to heat in the furnace. The colours used for the
painting of it are all derived from metals; and many of
them, though dull when applied, acquire considerable
lustre by the action of the fire. The colours are always
mixed with some kind of flux, such as a mixture of
glass (#204:n204#), borax (#208:n208#), and nitre, melted together,
and afterwards ground.
Gum or oil of lavender is used for mixing up the
colours. When the painting is finished, the pieces
are exposed to a heat sufficient to melt the flux, and
thus fix the colour.
119. TRIPOLI is a kind of clay of yellowish grey, brown,
or white colour, sometimes striped or spotted, and of an earthy
texture.
It feels harsh and dry to the touch; is soft, scarcely adheres
to the tongue, and will not take a polish from the nail.
This substance obtained its name from having formerly
been imported into Europe from Tripoli, on the
north coast of Africa. It is, however, now found in
several parts of Germany; and a granulated kind has
been discovered in England.
Tripoli is used for the polishing of metals and stones.
For this purpose, it is mixed with sulphur, in the proportion
of two parts of tripoli to one of sulphur. These are
well rubbed together on a marble slab, and are applied
to the stone or metal with a piece of leather.
When tripoli is combined with red ironstone, it is
used for the polishing of optical glasses. It is sometimes
made into moulds, in which small metallic or glass
figures and, medallions are cast; and a kind of tripoli is
found near Burgos, in Spain, which is used as an ingredient
in the manufacture of porcelain.
In Derbyshire,, and several parts of Staffordshire, is
dug a kind of tripoli which has the name of rotten stone.
This is considered to be a produce of limestone shale,
which has undergone a decomposition by exposure to
the air and moisture. It is used for most of the same
purposes as tripoli.
// 092.png
.pn +1
.sp 2
.h5
CLAY SLATE FAMILY.
120. CLAY SLATE, or ROOFING SLATE, is a kind
of stone of foliated texture, and greyish, black, brown, green,
or bluish colour.
It breaks into splinters, does not adhere to the tongue, yields
generally a clear sound when struck, and is nearly thrice as
heavy as water.
Vast and extensive beds of slate occur in different
parts of the world; and this mineral sometimes constitutes
even a principal portion of mountains. In our
own country there are many important quarries of it,
particularly in Westmoreland, Yorkshire, Wales, and
Derbyshire.
The uses of slate are numerous and important; but
its principal use is for the roofing of houses. For this
purpose it is split into thin plates or laminæ. These
are fastened to the rafters by pegs driven through
them; and are made to lap over each other at the edges,
in such manner as to exclude the rain and other
moisture. The kinds which are preferred for this purpose
are such as have the smoothest surface, and split
into the thinnest plates. It is requisite that slates should
be damp when they are split, otherwise this cannot be
done without difficulty. Hence it is generally customary
to split the masses as soon as possible after they
have been separated from the rock.
Slate should not be porous. If it be so, rain and
snow water will pass through it, and destroy the wood-work
of the house on which it is placed. Porous slate
is also liable to have moss and lichens grow upon and
cover it. These plants retain moisture long, and keep
the surface, and even the interior of the slate, moist; so
that, during the winter season, by the freezing of the
moisture, the slate is apt to split and fall into pieces.
To ascertain whether the slate be of requisite compactness,
it should be completely dried, then weighed, and
afterwards soaked for some time in water. When taken
// 093.png
.pn +1
out it is to be wiped with a cloth, and again weighed.
If it have not acquired any considerable increase of
weight, it is a proof of its being sufficiently compact.
If, on the contrary, it have absorbed much of the water,
and have become considerably heavier by the immersion,
it is shown to be of a porous texture. Slates that
are brittle are bad. If they emit a tolerably clear
sound, when struck with a hammer, it is considered a
proof that they are not too brittle: if, on the contrary,
the sound be dull, they are soft and shattery. A good
slate ought also to resist the action of a considerable
degree of heat.
The slates that are principally used in London are
brought from North Wales, from quarries that are
worked near Bangor. There are also extensive slate
quarries near Kendal, in Westmoreland; and the Kendal
slates, which are of a bluish green colour, are more
highly esteemed than those from Wales. They are not
of large size, but they possess great durability, and
give a peculiarly neat appearance to the roofs on which
they are placed. The slate quarries near Easdale, in
Scotland, are so extensive as to furnish annually more
than 5,000,000 in number, and to give employment to
upwards of 300 men.
French slates were much used in London about
seventy years ago; but they have been found too small,
thin, and light, to resist the winds and storms of this
changeable climate.
Dark-coloured, compact, and solid slates are manufactured
into writing slates, or table slates, as they
are sometimes called. In the preparation of these, the
slate, after it is split of proper thickness, is smoothed
with an iron instrument. It is then ground with sandstone,
and slightly polished with tripoli (#119:n119#), and,
lastly, rubbed with charcoal powder. It is cut into the
requisite shape, set in a wooden frame, and is then
ready for use.
For writing on these slates, pencils are used which are
also made of slate. These, which are called slate pencils,
// 094.png
.pn +1
are made of a particular kind of slate, that, on
splitting, falls into long splintery fragments. It is
necessary that the pencils should be considerably softer
than the slate to be written upon, so that they may
leave a whitish streak on its surface, without scratching
it. Such is the shivery nature of the slate of which
they are made, that, if it be exposed for some time to
the action of the sun or frost, it is rendered useless.
Hence, workmen are careful to cover it up and sprinkle
it with water, as soon as it is taken from the quarry,
and to preserve it in damp cellars. The pieces are
afterwards split by a particular instrument, and then
wrought into the requisite shape.
In some of the quarries in Derbyshire and Wales the
slate is so thick as to admit of being split into large and
tabular pieces. These are used for gravestones, and for
slabs for dairies and cellars. Paving stones and mile-stones
are also formed of them; and vessels for the salting
of meat, and setting of milk in dairies. For the latter
use slate is peculiarly well adapted, on account of
its resistance of greasy or oily substances. But this
property renders it unfit for any purpose for which it is
requisite to be painted; as, the oil not entering the
stone, the paint soon peels off, and leaves the stone as
black as it was at first. Cut into narrow strips, slate has
also been applied, in the neighbourhood of Bangor,
North Wales, for the formation of fences.
When sufficiently solid for the purpose, slate is cut
into inkstands, and turned into vases, and fancy articles
of various kinds. And a singular circumstance has been
remarked, that, if a window or door be suddenly opened,
in an apartment where the workmen are turning these,
they will sometimes fly in pieces; though, after the
work is finished, they may be exposed to the usual
changes of temperature without injury.
Pounded slate is advantageously used for cleaning
iron and other works in metal. When well ground, and
mixed with a certain proportion of loam, slate is made
into moulds for the casting of metals in; and, when
// 095.png
.pn +1
burned and coarsely ground, is used instead of sand in
the making of a solid and impermeable mortar or
cement, for the parts of buildings that are covered with
water.
121. BLACK CHALK, or DRAWING SLATE, is an
earthy substance, of slaty texture; generally of a greyish,
sometimes a bluish black colour.
It is soft and smooth to the touch, and, in handling, stains the
fingers.
To crayon painters, and other artists, black chalk is
a very useful article. Considerable quantities of it are
imported from France, Spain, and Italy. The best is
brought from Italy. This is more free from gritty particles,
more firm and compact in its texture, and in its
touch much smoother than the chalk of any other country.
It contains somewhat more than one-tenth part of
its weight of charcoal. When prepared for use, it is
cut into square pieces, which are sometimes enclosed
in wooden cases, like black lead pencils. These pencils
are said to become dry, hard, and unfit for use, by
long keeping. To preserve them in greatest perfection,
they should be kept in a moist place. Some artists
prefer pencils that are made of the chalk finely ground,
mixed with a certain proportion of gum water, and cast
in moulds. Care should be taken not to put too much
gum, as the pencils will not, in such case, leave any
mark on the paper.
Drawing slate is sometimes used as a black colour
for painting. For this purpose it is pounded or ground,
and then mixed with oil or size, according to the kind
of work for which it is required. When black chalk is
strongly heated, it loses its colour, and assumes that of
a reddish grey.
122. HONE, or WHET SLATE, is a well-known kind of
stone, of somewhat slaty texture, and generally of dull white,
or greenish grey colour. Its surface is smooth, and feels unctuous
to the touch.
// 096.png
.pn +1
These stones, when properly cut and smoothed, are
of indispensable utility to carpenters, cutlers, and others,
for sharpening their cutting instruments upon. Those
of the finest grain are used for lancets, penknives, and
razors. For this purpose their surface, when used, is
covered with a small quantity of oil; by which, after
a while, they are rendered considerably harder than
they were at first. They ought to be kept in damp and
cool places; for, if much exposed to the sun, they become
too hard and dry for many purposes to which they
are applied.
There is a vulgar and erroneous notion that hones
are holly wood, which by lying in petrifying water,
have been thereby converted into stone. The greater
number of them have a fine and a coarse side. From
the circumstance of their having been originally brought
into this country from Turkey and the Levant, they are
sometimes called Turkey stones. They are now found
in Saxony and Bohemia, in North Wales, and near
Drogheda, in Ireland.
The powder of whet slate is sometimes used, instead
of emery, for the cutting and polishing of metals.
.sp 2
.h5
MICA FAMILY.
123. COMMON MICA, GLIMMER, or MUSCOVY
GLASS, is a mineral substance of foliated texture, which is
capable of being divided into extremely thin leaves that have
a sensible elasticity, and are transparent.
The colour of mica is greenish, sometimes nearly black, reddish,
brown, yellow, or silvery white, with, occasionally, a metallic
lustre on the surface. Mica is so soft as easily to be
scratched; and, when divided across the plates, seems rather
to tear than break.
This is one of the most abundant mineral substances
that is known. It not only occurs in a massive and
crystallized state, but it enters into the composition of
many rocks; is found filling up their fissures, or crystallized
// 097.png
.pn +1
in the cavities of the veins which traverse them.
In some countries, as in Siberia, it is an article of
commerce, and is obtained from mines like other minerals.
From these it is extracted by hammers and
chisels. It is then washed, to free it from the impurities
which adhere to it; split into thin leaves or pieces;
and assorted into different kinds, according to their
goodness, purity, and size. We are informed by the
Abbé Haüy, that plates of mica a yard or more in width
have been obtained from the mines in some parts of
Russia.
Thin plates of mica are adopted, in many parts of
Siberia and Muscovy, to supply the place of glass for
windows. In the shipping of Russia it is considered
preferable to glass, as the concussion produced by the
firing of the guns does not shatter it. It is employed
instead of window glass in Peru and New Spain; and
also in Pennsylvania. Mica may be advantageously
substituted for horn in lanterns, as it is not only more
transparent, but is not susceptible of injury from the
flame of the candle. It has, however, the inconvenience
of soon becoming dirty; and of having its transparency
destroyed by long exposure to the air. Mica is used
for enclosing objects that are intended to be viewed by
microscopes.
So plentiful is this substance in Bengal, that, for the
value of five shillings, as much of it may be purchased
as will yield a dozen panes, each measuring about twelve
inches in length and nine in breadth, and so clear as to
allow of ordinary objects being seen through them at
the distance of twenty or thirty yards.
Mica, when powdered, is sold by stationers on the
Continent, in place of sand, for absorbing ink in writing,
but it does not dry sufficiently quick to be of much
use in this respect. In Russia it is employed in different
kinds of inlaid work. It is sometimes powdered, and
intermixed with the glaze in particular kinds of earthen
ware. The heat which melts the glaze has no effect on
// 098.png
.pn +1
the mica: hence it appears, dispersed throughout the
glaze, like plates or scales of silver or gold. Some
artists use it in making artificial avanturines (#85:n85#).
It must be observed that the best mica is of a pure
pearl colour; and, when split into leaves, presents a
smooth surface.
.sp 2
.h5
SOAPSTONE FAMILY.
124. STEATITE, or SOAPSTONE, is a soft and unctuous
substance, which has much the appearance of soap; and
is generally of a white or grey colour, intermixed with greenish
or yellowish shades.
It is somewhat more than twice as heavy as water; and is
distinguished from indurated talc (#135:n135#) by not splitting, like
that substance, into slaty fragments.
In the counties of Devon and Cornwall, and the
islands in the vicinity of the Lizard Point, this mineral
is found in considerable abundance. It possesses many
of the same properties as fullers’ earth, and is, like that
substance, employed in the scouring of woollen cloths.
When mixed with water it may be formed into a paste;
and, in this state, it is easily worked, like clay, for the
manufacture of earthen ware. In the porcelain manufactory
at Worcester considerable quantities of steatite
are employed. According to Dr. Shaw, the Arabs use
it in their baths, instead of soap, to soften the skin.
As it becomes hard in the fire, and does not alter
its shape, this substance has been successfully adopted
for imitations of engraved gems. The subjects are engraved
upon it with great ease in its natural state; it is
then exposed to a strong heat; afterwards polished,
and then coloured by means of certain metallic solutions.
We are informed by travellers, that some of the savage
tribes eat steatite, either alone, or mixed with their
food, to deceive hunger. The inhabitants of New
Caledonia eat considerable quantities of it. Humboldt,
the South American traveller, assures us that the Otomacks,
a savage race of people, who live on the banks
// 099.png
.pn +1
of the Orinoco, are almost wholly supported, during
three months of the year, by eating species of steatite,
or potter’s clay, which they first slightly bake, and then
moisten with water. M. Golberry says that the negroes
near the mouth of the Senegal mix their rice with
a white kind of steatite, and eat it without inconvenience.
In some parts of Spain a variety of steatite is found,
which is used by artists under the name of Spanish chalk.
When slightly burned, this mineral is sometimes used as
the basis of rouge.
125. Figure Stone is a kind of steatite, which has,
internally, a glimmering and resinous lustre, and a slaty
or splintery fracture.
From its softness, and yet solidity of texture, this
mineral can easily be fashioned into various shapes, even
with a knife. Hence in China, where it frequently
occurs, it is cut into grotesque figures of various kinds,
which the French call magots de la Chine, into cups,
vases, pagodas, snuff-boxes, and other articles.
126. MEERSCHAUM, or SEA-FROTH, is a singular
kind of mineral, of yellowish or greyish white colour, sometimes
so light as to float in water: when fresh dug it has
nearly the consistence of wax.
If exposed to a strong heat, it becomes so hard as to yield
sparks with steel.
The principal use to which meerschaum is applied is
in the formation of the bowls or heads of tobacco-pipes
used by the Turks, and the quantity consumed for this
purpose is very great. It is found in a fissure of grey,
calcareous earth, about six feet wide, near Konie, in
Natolia, where upwards of six hundred men are employed
in the digging and preparation of it; and the
sale of it supports a monastery of dervises established
at that place. The workmen assert that it grows again
in the fissure, and puffs itself up like froth. It is prepared
for use by being first agitated with water in great
// 100.png
.pn +1
reservoirs, then allowed to remain at rest for some time.
The mixture soon passes into a kind of fermentation,
and a disagreeable odour, resembling that of rotten
eggs, is exhaled. As soon as this smell ceases, the
mass is further diluted with water, which, after a while,
is poured off. Fresh water is repeatedly added, until the
mass is sufficiently washed and purified. The meerschaum,
in this state, is dried to a certain degree. It
is then pressed into a brass mould, and, some days
afterwards, is hollowed out so as to form the head of
the pipe. It is subsequently dried in the shade, and
lastly is baked. In this state the pipe heads are brought
to Constantinople, where they are subjected to further
processes. They are first bailed in milk, and next in
linseed oil and wax; and, when perfectly cool, are
polished with rushes and leather. The boiling in oil
and wax renders them capable of receiving a higher
polish than could otherwise be given. When thus impregnated,
they also acquire, by use, various shades of
red and brown, which are thought to add considerably
to their beauty. In Turkey, and even in Germany,
meerschaum pipes that have been much used are more
valued than those newly made, and this solely on account
of the colouring they possess. Indeed there are
people in those countries whose only employment consists
in smoking tobacco pipes, until they acquire the
favourite tints of colour. By long use, the heads become
black: but if boiled in milk and soap, they are
soon rendered white again.
It is asserted that the Turks spread meerschaum on
bread, and eat it as a medicine; and that they cover
with it the heads and eyes of dead bodies, previously
to interment. As it lathers with water like soap, it is
used by the Turkish women for washing their hair;
and, as it absorbs oily matters, it is occasionally used,
as fuller’s earth is with us, for the cleansing and scouring
of cloth.
We are informed by Pliny, that a kind of bricks were
made by the ancients, so light that, when dried, they
// 101.png
.pn +1
would float in water. He describes them to have been
formed of a spongy kind of earth, and to have had some
resemblance to pumice stone, which he says might perhaps
be applied to the same purposes as these bricks,
if it could be obtained and wrought in sufficient quantity.
Bricks of similar description have lately been
made of a mineral substance found near Sienna, in
Italy, and which is supposed to be meerschaum.
A kind of meerschaum has lately been discovered,
in veins, in the serpentine (#132:n132#) of Cornwall.
127. BOLE is an earthy mineral, of yellowish or reddish
brown colour, soft, and somewhat unctuous to the touch, and
generally found in a massive state.
It exhibits internally a glimmering lustre; and, when put
into water, immediately absorbs it, and breaks down into small
pieces with a crackling noise. This mineral is farther distinguished
by its fracture being conchoidal, or appearing somewhat
like the impression of a shell; and by its adhering
strongly to the tongue.
Although bole is at present little used except as a
basis of tooth powder, and a coarse kind of paint, it
was formerly considered an important article in medicine,
and used as an astringent. We are informed that
tobacco pipes are sometimes made of this mineral; and
that it is employed as an ingredient in the glaze of some
kinds of earthen ware.
It is chiefly imported from the Levant; though it
has also been found in considerable beds in Silesia and
Saxony.
128. LEMNIAN EARTH is a kind of bole of yellowish
grey, or yellowish white colour, sometimes marbled with rust-like
spots.
It is distinguished from bole by being dry and not unctuous
to the touch, dull internally, adhering slightly to the tongue,
and its fracture being earthy.
With the ancients this mineral was considered an almost
invaluable medicine. They procured it chiefly
// 102.png
.pn +1
from Armenia, and the island of Lemnos, in the Grecian
Archipelago. The Lemnian bole was held so sacred
that it was dug in the presence of the priests of Venus,
and, after having been mixed by them with goat’s blood,
was moulded into cakes, which were impressed with
the figure of a goat, to authenticate them. This done,
it was administered as a consecrated remedy; and, even
so lately as the sixteenth century, the vein of bole in
Lemnos was annually opened on the sixth of August,
and, after certain prayers by the priests, so much of
the earth was taken out as was thought sufficient for
the consumption of the ensuing year. The entrance
was then closed, and the severest punishments were
denounced against any one who should open it without
permission. A portion of the earth was sent to Constantinople,
where it was made into small cakes, and
sealed by the ministers of the Emperor; the remainder
was prepared in the island, and was impressed with the
seal of the Governor. Not many years ago, it was customary
with certain empirics on the Continent, to sell
this substance in sealed packets, as a nostrum of great
value, and particularly as possessing astringent properties
of very extraordinary nature.
129. FULLER’s EARTH is a well-known mineral, generally
of greenish colour, more or less mixed with brown,
grey, or yellow: of soft and almost friable texture, and
somewhat unctuous to the touch.
When put into water it immediately absorbs it, and breaks
down into a fine pulp.
This earth is valuable for its property of taking grease
out of woollen and other cloths, which, on a large scale,
is effected by the operation called fulling, whence its
name has been derived. This operation, which is performed
by a kind of water mill, called a fulling mill, is
particularly necessary with respect to new cloths, to
extract from them the grease and oil that have been
used in their preparation.
Fuller’s earth was formerly considered an article of
// 103.png
.pn +1
such importance in England that its exportation was
prohibited under severe penalties. It was then employed
for most of those purposes for which soap has
since been so extensively applied. In the dressing of
cloth it is now so indispensable, that foreigners, although
they can procure the wool, are never able, without
fuller’s earth, to reach the perfection of the English
cloths: and, in this country, incalculable quantities of it
are consumed. As an article of domestic utility, it
might be much more frequently used than it is, as a
substitute for soap, in the cleaning and scouring of
wooden floors and wainscots.
There are extensive beds of fuller’s earth in several
of the counties of England. London is principally
supplied from those of Kent, Sussex, and Surrey. At
Wavedon, near Woburn, in Bedfordshire, a peculiarly
fine kind is dug up from pits at the depth of ten or
twelve feet below the surface of the ground; and no
country in the world is known to produce fuller’s earth
of quality so excellent as that obtained in England.
.sp 2
.h5
TALC FAMILY.
130. JADE, or NEPHRITE, is a very hard and tough
species of stone, of greenish or olive colour, somewhat unctuous
to the touch, and looking as if it had imbibed oil.
It is found massive, in blunt-edged or rounded pieces.
Nothing has so much tended to make this stone known,
as a superstitious notion that a piece of it suspended to
the neck will dissolve stones in the kidneys. Hence
has been attained its appellation of nephrite, or divine
stone; and hence have originated all those numerous
amulets in the form of oval plates, hearts, fishes, birds,
&c. pierced with holes for ribbons to pass through,
which are seen in collections of the curious. Some of
the Indian nations make talismans of jade.
From the roughness and tenacity of this stone, in
addition to its hardness, it is very difficult to be cut
and polished; and even the best polish which it is
// 104.png
.pn +1
capable of taking as so imperfect, that a person ignorant
of its nature might consider it to be merely smoothed
and rubbed with oil. The ancient artists executed in
it many beautiful and delicate figures; and it is impossible
but to admire the industry and perseverance by
which they produced even chains, and other hollow
kinds of work, in jade.
The Turks cut it into handles for sabres and daggers,
and into several kinds of vessels, to which they attach
great value.
Jade occurs in granite (#251:n251#) and gneiss (#255:n255#) in Switzerland;
but the most beautiful specimens of this mineral
are brought from Persia, Egypt, and Siberia.
131. Axestone is a kind of jade, but differs from it in
having a slaty texture; and in being less transparent and
less tough. This stone is found in China, New Zealand,
and on the banks of the river of Amazons, in America.
And it is said that several of the tribes of American
Indians form of it the axes which they use in place of
iron. To explain how these people have been enabled
to work a substance so rebellious as this is even to the
file, and to other instruments of steel (of which they
know not the use), it has been presumed that, when the
stone is first taken from the earth, it is considerably less
hard than when, by drying, its humidity is evaporated:
that in this state they work it, and subsequently harden
it, in some peculiar manner, by exposure to heat.
132. SERPENTINE is a stone which, when polished,
has a near resemblance to marble, is of dark green colour, or
reddish; variously streaked, and spotted with lighter green,
red, brown, and yellow.
It is found in beds, and in a massive state; is translucent
at the edges; and, when pounded, the powder feels soapy to
the touch.
There are few stones likely to prove more valuable in
ornamental architecture, both for beauty and durability,
than this. It admits of an excellent polish, which
is not easily injured by the effects of air or water. It
// 105.png
.pn +1
is also too hard to suffer the same inconveniences of
being scratched or broken as marble; and its colours
are stated to be indestructible. And such is the size of
many of the blocks of serpentine, that columns of almost
any dimensions may be wrought out of them.
Of the serpentine obtained from the Island of Anglesea,
and lately known by the name of Mona marble, a
great proportion was sent to London by Messrs. Bullock
and Co. who, until the death of Mr. Bullock, had a large
warehouse and polishing rooms for it in Oxford-street.
The prevailing colours of this stone are red and
green. The quarries were worked by them to considerable
extent. They manufactured it into chimney
pieces, slabs, columns, and other articles; and its great
beauty, and its excellence, in many respects, over the
generality of marbles, will recommend it strongly to the
public notice.
The chief places in which serpentine has hitherto
been found are near Bareuth, and Zöblitz, in Saxony;
in some districts of Cornwall; about six miles west of
the Paris copper mine, in the island of Anglesea; at
Portsoy, in Bamffshire, and other parts of Scotland;
and at Cloghan Lee, in the county of Donegal, Ireland.
At Zöblitz there are some extensive manufactories,
in which serpentine is made into vessels and ornaments
of various shapes, that are carried for sale over nearly
all parts of Germany. Several hundred persons are
there employed in the working of this stone.
The name of serpentine is derived from some of the
varieties appearing coloured and spotted like a serpent’s
skin. This stone, when found intermixed with primitive
limestone, or crystalline white marble, differs in no respect
from the celebrated verde antique marble (#149:n149#).
133. POTSTONE, or LAPIS OLLARIS, is a greenish
grey stone, unctuous to the touchy and so soft when first taken
from the quarry as to yield to the pressure of the nail, yet not
easily broken.
It is found in a massive state.
// 106.png
.pn +1
In consequence of the softness and tenacity of this
stone, it can be turned upon a lathe, and otherwise
cut and wrought with great ease. Hence, in Egypt,
Lombardy, Norway, and other countries where it is
found, it is formed into various kinds of culinary vessels
and lamps, which harden in drying, and are capable of
withstanding the strongest action of fire. Vessels of
this description were known to the ancients; and are
particularly mentioned by Pliny, the Roman naturalist,
who speaks of some that were highly wrought being
very valuable.
Potstone is used in some countries for the lining of
stoves, furnaces, and ovens; and it is so durable as to
have, in some instances, stood unimpaired for several
hundred years.
On the banks of the Lake Como, there were some
extensive quarries of potstone, which had been worked
from the beginning of the Christian era. These quarries,
however, fell in, on the 25th of August, 1618, and
destroyed the neighbouring town of Pleurs; which had
previously obtained by means of them an annual revenue
of about sixty thousand ducats.
134. COMMON, or VENETIAN TALC, is an earthy
stone, capable of being divided into plates or leaves, which
are soft and unctuous to the touch, somewhat transparent, and
usually of greenish silvery white colour.
It leaves a white trace when rubbed upon any object.
Mica and talc have a near resemblance to each other; but
the plates of the former, when bent, are elastic, while those of
the latter are not.
Venetian talc is very abundant in the Tyrol and the
Valteline. In a state of powder it renders the skin soft
and shining; a property which appears to have suggested
the idea of employing it as the basis of the
cosmetic named rouge. This is prepared by rubbing
together, in a warm mortar, certain proportions of carmine,
or extract of the flowers of carthamus tinctorius,
// 107.png
.pn +1
with finely powdered talc, and a certain portion of oil
of benzoin.
The Romans prepared a beautiful blue or purple
colour, by combining pounded talc with the colouring
fluid of some particular kinds of testaceous animals,
that are found among the submarine rocks of the coasts
of the Mediterranean. According to Tavernier, the
French traveller, the Persians whiten the walls of their
houses and gardens with lime, and then powder them
with a silvery white kind of talc; which, he says, gives
to them a very beautiful appearance. Talc is now used
by the Chinese, and was formerly used by the Europeans,
in medicine,
135. INDURATED TALC, or FRENCH CHALK,
is a heavy mineral, of close texture, and generally of greenish
grey colour; unctuous to the touch, and having a somewhat
slaty fracture.
It is found in a massive state; and leaves a white trace
when rubbed upon any object.
This is a well known substance, which is in great
request by carpenters, tailors, hat-makers, and others,
as the lines that are drawn with it are not so easily
effaced as those that are made with chalk, and particularly
as they remain unaltered even under water. If
lines be traced with it on glass, they remain invisible, or
at least are scarcely perceptible by the naked eye, till
breathed upon. This, it has been conjectured, in part
depends on the comparative softness of the substance
with which the impression is made; the condensation
of the breath taking place more readily on the glass
than on the talc that covers it, and the impression of
the talc becoming more apparent by the contrast.
Indurated talc, when reduced to powder, is frequently
employed for the purpose of removing stains, occasioned
by grease, from silk and cloth. This it does effectually,
and, in general, without injuring even the most delicate
colour. Like potstone, it is sometimes manufactured
into culinary vessels.
// 108.png
.pn +1
This mineral is found in several parts of the continent
of Europe; and in Cornwall, Scotland, and the Shetland
Islands.
136. ASBESTOS is a greenish or silvery white mineral,
of fibrous texture, which is found in many mountainous countries
of the Continent, in the island of Anglesea, and in
Scotland. It occurs in shapeless masses, and varies much both
in weight and hardness.
The name of asbestos is derived from the Greek language,
and signifies that which is inconsumable. This
mineral, and particularly a silky variety of it, in long
slender filaments, called amianthus, was well known to
the ancients. They made it into an incombustible kind
of cloth, in which they burned the bodies of their dead,
and, by which means, they were enabled to collect and
preserve the ashes without mixture. In the manufacture
of this article they were not able to weave the asbestos
alone; but, in the loom, were obliged to join with it linen
or woollen threads, which were afterwards burned away.
Incombustible cloth was purchased by the Romans
at an enormous expense. Sir J. E. Smith, when at
Rome, saw a winding sheet of amianthus in the Museum
of the Vatican. It was coarsely spun, but as soft and
pliant as silk. The person who attended him set fire to
one corner of it; and the same part burned repeatedly
with great rapidity and brightness, without being at all
injured. This interesting relic was discovered, in the
year 1702, in a funeral urn, and contained burned
bones, together with a quantity of ashes. It was nine
Roman palms long, and about seven in width, and had
been deposited in the library of the Vatican by order of
Pope Clement the Eleventh.
Cloth made of amianthus, when greased, or otherwise
contaminated with dirt, may be cleansed by throwing
it into a bright fire. In this process the stains are
burned out, and the cloth is restored to a dazzling
white colour. Pliny, the Roman naturalist, informs us
that he had himself seen table-cloths, towels, and napkins
// 109.png
.pn +1
of amianthus taken from the table of a great feast,
thrown into the fire, and burned before the company:
and by this operation, he says, they became better
cleansed than if they had been washed.
The inhabitants of some parts of Siberia manufacture
gloves, caps, and purses of amianthus; and in the
Pyrenees it is wrought into girdles, ribbons, and other
articles. The finest girdles are made by weaving the
most beautiful and silky filaments with silver wire.
These are much prized by the women, not only on
account of their beauty, but from certain mysterious
properties they are supposed to possess.
The shorter fibres of amianthus have sometimes been
manufactured into paper, but this is too hard for use.
It has, indeed, been proposed to preserve valuable documents
from fire, by writing them on paper made of
amianthus. Such a plan might deserve consideration,
if we possessed fire-proof ink; but until this be obtained,
the fire-proof paper will be of little use.
When several of the long fibres of this mineral are
placed together, they may be formed into wicks for
lamps; and it has been asserted that such wicks are
incombustible. Kircher, the German philosopher, had
a wick made of amianthus which burned for two years
without injury, and was at last destroyed by accident.
It is said that the inhabitants of Greenland make use of
amianthus for the wicks of their lamps.
This substance, although it will long continue unaltered
in considerable heat, yet if the heat be much increased
it ceases to withstand it, and is melted into a
dense kind of scoria. In the island of Corsica asbestos
is advantageously employed in the manufacture of pottery.
Being reduced into fine filaments, it is kneaded
with clay; and vessels made of this mixture are said
to be lighter, less brittle, and more capable of sustaining
sudden alterations of heat and cold than common
earthenware.
// 110.png
.pn +1
.sp 2
.h5
CHRYSOLITE FAMILY.
137. CHRYSOLITE, or PERIDOT, is a soft gem,
usually of yellowish green colour, though sometimes it is
grass-green, or bluish green, but with a tinge of brown.
It is generally found in fragments and rounded pieces, and
rarely crystallized. In the latter case its regular form is an
eight, ten, or twelve-sided prism.
Though scarcely harder than glass, and consequently
inferior to most other gems in lustre, these stones are
not unfrequently used in jewellery, particularly for
necklaces and ornaments for the hair; and, when well
matched in colour, and properly polished, their effect
is very good. They are, however, too soft for ring
stones; for, by wearing, they soon become dull on the
surface. But it is said that their lustre may, in some
degree, be restored by immersing them in olive oil.
To give the greatest brilliancy to this stone, we are
informed by Mr. Mawe, that a copper wheel is used,
on which a little sulphuric acid, or spirit of vitriol (#24:n24#),
is dropped; and that, during the process, an highly
suffocating odour is given out. But he is of opinion
that the most advantageous way of working it would be
that in which glass is cut.
Chrysolite is imported from the Levant, and is said
to be found in Upper Egypt, and on the shores of the
Red Sea.
.sp 2
.h5
BASALT FAMILY.
138. BASALT is a greyish black and coarse grained stone,
which is usually found either in globular distinct pieces or in
groups of large columns, each of which has from three to eight
sides, and is divided horizontally into numerous stones, that
very exactly lie upon, or fit into each other.
The most remarkable assemblages of basaltic columns
that are known are those called the Giants’ Causeway,
on the coast of Antrim, in Ireland, and the Cave
of Fingal, in the island of Staffa, one of the Hebrides,
or Western Islands of Scotland.
// 111.png
.pn +1
The former, which is believed by the common people
to have been an artificial production, the vast labour of
giants who formerly inhabited the country, consists of
an irregular group of many thousand jointed pillars.
Most of these are of considerable height; are in general
five-sided, fifteen or sixteen inches in diameter,
and each perfectly distinct from top to bottom, though
so closely and compactly arranged that it is scarcely
possible to introduce any thing betwixt them. This
assemblage of columns extends into the sea to a distance
unknown, and along a tract of the sea coast of
nearly six miles.
The Cave of Fingal is accessible only by sea, and is
formed by ranges of massive basaltic columns, fifty feet
and upwards in height. The stone of which these columns
are formed very much resembles that of the
Giants’ Causeway.
In several parts of the world large masses of basalt
are discovered, composing entire insulated mountains,
of somewhat conical form. They are considered by
some writers as volcanic productions, but the proofs of
this are by no means satisfactory.
Amongst the uses to which basalt has been applied,
two of the most important are as materials of an excellent
and durable kind for building and paving. When
burned and pulverized, these stones impart to mortar
with which they are mixed the property of hardening
under water. They easily melt, without any addition,
into an opaque and black glass; and from them, under
a certain modification, bottles of olive-green colour, and
of extreme lightness, but great strength and solidity,
have been formed. Some of the kinds have been advantageously
employed as millstones. Basalt is occasionally
used by artists for touch or teststones, to ascertain
the purity of gold and silver; and goldbeaters
and bookbinders, on the Continent, usually make their
anvils or beating blocks of it.
Basalt, though harder, more brittle, and less pleasing
in its colours than marble, was in considerable esteem
// 112.png
.pn +1
among the sculptors of antiquity, on account of its great
durability. Many fine works were consequently executed
by them in this stone. Pliny, who has described
several, states that the columns of it were sometimes so
large as to admit of several figures being wrought out
of them. The Emperor Vespasian had an entire statue,
accompanied by the figures of sixteen children, cut out
of a single column of basalt; this statue he placed in
the Temple of Peace, and dedicated it to the Nile.
The famous statue of Minerva, at Thebes, is described
by travellers to have been formed of basalt. Antiques
of basalt are always in a much better state of preservation
than those of marble. Even such as are dug out of
the earth still retain their original polish; and the
finest touches of the chisel upon them are still unimpaired.
.sp 2
.pb
.sp 4
.hr 10%
.h4
ORDER III.—SALINE STONES.
.hr 10%
.sp 2
.h5
LIME, OR CALCAREOUS FAMILY.
139. Lime, after it has been freed from extraneous
matters by burning, is a mineral of whitish colour, and pungent,
acrid, and caustic taste. It has the property of changing vegetable
blue colours to green, and of corroding and destroying animal
substances.
This mineral is found in nearly every country of the
globe: but, in a native state, has not hitherto been discovered
except in combination with some acid.[#] The
// 113.png
.pn +1
process of purifying lime, or depriving it of the acid
with which it is combined, is by burning. This is done
in a large kind of furnace, called a kiln, where the
limestone and fuel are heaped in alternate layers. After
it has gone through this process it is called quick-lime,
and has the above-mentioned appearance and qualities.
.pm fn-start // A
With carbonic acid (#26:n26#) it forms common limestone, marble,
chalk, and some other substances; with sulphuric acid (#24:n24#) it
constitutes alabaster, or gypsum; and with fluoric acid (#27:n27#) it
becomes that beautiful production, the Derbyshire spar.—All
these, having lime for their bases, are denominated CALCAREOUS
SUBSTANCES.
.pm fn-end
The uses of lime are numerous and important. The
principal of these is in the formation of mortar, or
cement for buildings. For this purpose it is first slaked,
by having water poured upon it: a violent heat is thereby
excited, and the lime falls into powder: it is then
formed into paste by working it with water and sand.
This, when dry, becomes extremely solid, hard, and
durable. Various examples might be mentioned of
buildings nearly two thousand years old, where the lime
is, at this day, as hard as the stones which it cements
together. Lime is also used for agricultural purposes:
when spread upon land it is supposed to hasten the dissolution
and putrefaction of all kinds of animal and
vegetable substances, and to impart to it a power of
retaining the moisture which is necessary for the vigorous
growth of corn or grass. It is employed in the
refining of sugar, in the manufacture of soap, in the
melting of iron, and by tanners, in a state of solution,
for dissolving the gelatinous parts of skins, and removing
the hair from them. The manufacturers of glue
mix it with that article, for the purpose of adding to its
strength, and preventing its becoming flexible by the
absorption of moisture. This mineral, if well dried,
pounded, and mingled with gunpowder, in the proportion
of one pound to two, is of great utility in the rending
of stones and rocks: the mixture, it is said, will
cause an explosion equal in force to three pounds’ weight
of gunpowder. Lime, if swallowed or inhaled, is a virulent
poison. Hence persons employed in lime-works
are subject to very distressing complaints; and hence,
if bread be adulterated with lime, it is extremely injurious.
Notwithstanding this pernicious quality, lime is of
considerable use in medicine. It is chiefly given in a
// 114.png
.pn +1
state of solution, and in the proportion of half a pound
of quick-lime to twelve pints of boiling distilled water.
This preparation is called lime water.
The superb basin of Lampi, one of the principal reservoirs
which furnishes the canal of Languedoc with
water, was, some years ago, found to leak at the junction
of the stones. The engineer who had the direction
of the works caused lime to be slacked in the water.
This, passing through the apertures betwixt the stones,
formed a crust, or very white covering, over its whole
surface, of so hard and durable a nature, that it now
constitutes one solid and undivided substance, which
the water cannot penetrate.
CARBONAT OF LIME.
140. COMMON LIME is a variety of carbonat of lime,
or of lime in combination with carbonic acid (#26:n26#), which is
harder and heavier than chalk, usually of a greyish colour, and
is always found in a massive state.
Vast mountains of limestone occur in several countries
of the globe; but no where is lime more abundant
than in some parts of England and Wales. It forms,
in particular, nearly the whole mountainous districts of
Derbyshire and Shropshire, and encloses, in its substance,
numerous veins of lead ore, calamine, and other
important mineral productions.
Its uses have been already described (#139:n139#).
141. CHALK is a white or yellowish kind of limestone, too
well known to need any description.
It is found abundantly in many of the southern counties
of England, and is usually procured from large
open places, called chalk-pits, by digging. In some
parts of Kent, however, the workmen save themselves,
in this respect, much trouble. They undermine the
sides of hills to a certain depth, then dig a trench at
the top as far distant from the edge as the mining extends
at the bottom. This trench they fill with water,
which soaks through during the night, and the whole
// 115.png
.pn +1
mass is thereby loosened, and falls down before morning.
The harder and more compact kinds of chalk are cut
into blocks, and used as building stones. When burned
and formed into lime, chalk becomes an excellent mortar:
nearly all the houses in London are cemented with
chalk mortar. It is also used as lime in agriculture.
As it readily imbibes water, it is used by starch-makers,
chemists, and others, to dry precipitates upon. With
isinglass or the white of eggs it forms a valuable lute or
cement. By artists it is in request for the construction
of moulds to cast metals in; and by carpenters and
others, as a material to mark with. Chalk is one of the
most useful absorbents that are employed in medicine:
it likewise gives name to an officinal mixture, to a powder,
and a potion.
When pounded and cleared from gritty particles, it
has the name of whiting. In this state it is used for the
cleaning and polishing of metallic and glass utensils;
for whitening the ceilings of rooms, and numerous other
purposes. Spanish white is the same substance cleansed
with peculiar care; and the Vienna white, which is used
by artists, is perfectly purified chalk.
142. MARBLE is a compact and close-grained kind of
limestone; so hard as to admit of being polished. It is this
quality which principally distinguishes it from other calcareous
substances.
Although nearly all the numerous kinds of marble
may be burned, and thus converted into quick-lime,
their use in ornamental architecture, &c. is so important
as, in general, to prevent their application to the inferior
purpose of mortar. Marble has been known from
a very early period. The Book of Esther, in the Old
Testament, describes the palace of Ahasuerus to have
had “pillars of marble,” and the pavement of “red,
and blue, and white, and black marble.”
It would be impossible, in an elementary work like
the present, to describe, or even to enumerate, all the
different kinds of marble which were known to the ancients,
// 116.png
.pn +1
or are known to the moderns. But it is, perhaps,
requisite that an account should be given of some of
the most important of them.
GREEK MARBLES.—143. Pentelic Marble is
of beautiful white colour, and nearly resembles the Parian
marble (#145:n145#) of the Italians; but it is in coarser granulations.
Sometimes it is splintery. It was obtained
from quarries on Mount Pentelicus, near Athens, and
was generally preferred, by the Grecian artists, to Parian
marble. The Pantheon was built entirely of Pentelic
marble; and many of the Athenian statues, and
works carried on near Athens during the administration
of Pericles, were executed in it. Dr. Clarke, however,
has observed that while the works wrought of Parian
marble remain perfect to the present time, those of
Pentelic marble have been decomposed by the atmosphere,
and sometimes exhibit a surface as rude and
earthy as common lime-stone. There are numerous examples
of Pentelic marble in those works of Phidias
which form the Elgin collection in the British Museum.
144. Greek White Marble.—The Marmo Greco, of
Italian artists, is of snow-white colour, in fine granulations;
and somewhat harder, and consequently capable of
higher polish, than most other white marbles. It is
found near the river Coralus, in Phrygia.
ITALIAN MARBLES.—145. Parian Marble is
of snow-white colour, inclining to yellowish white. It is
obtained from quarries in the island of Paros, is finely
granular, and, when polished, has somewhat of a waxy
appearance. Parian marble hardens by exposure to the
air, and is one of the most permanent kinds that is
known. Varro and Pliny each state that it was named
lychnites, by the ancients, from a Greek word signifying
a lamp, because it was generally hewn in quarries by the
light of lamps. The finest Grecian sculpture that has
been preserved to the present time is of Parian marble.
The principal statues of it now extant are the Medicean
// 117.png
.pn +1
Venus, the Diana Venatrix, and Venus leaving the
Bath. It is also Parian marble on which the celebrated
tables at Oxford are inscribed.
146. Carrara Marble, the purest of all the kinds
with which we are acquainted, is to this day obtained
from quarries near the town of Carrara. It is of brilliant
white colour, has a granular texture; and, when
broken, sparkles like sugar. This marble, which is almost
the only one in use by modern sculptors, was also quarried
and wrought by the ancients.
It is susceptible of a high polish, and is applicable to
every species of sculpture, except when, as is too often
the case, dark veins intrude, and spoil the beauty of the
work. In the centre of the blocks a beautiful kind of
rock crystals, called Carrara diamonds, are sometimes
found.
During the late war with France, the exportation of
statuary marble from the countries under the dominion of
Buonaparte was prohibited; and, at one time, it became
so scarce in England as to be sold at the rate of more
than seven guineas per cubic foot. The block of marble
for the statue of his late Majesty in the great Council
Chamber at Guildhall, London, was stated by the
public prints to have cost twelve hundred guineas.
147. Luni Marble is a snow-white, compact, and
finely granular variety, which was obtained by the ancients
from quarries on the coast of Tuscany. It was
preferred by the Grecian sculptors, both to the Parian
and Pentelic marbles; and it is usually supposed that
the Belvidere Apollo, as well as the Antinous of the
Capitol, was wrought out of this marble. There is now
found at Luni a white marble, variegated with red spots
and dots.
148. Green antique Marble, or Verde antique
of the Italians, is a mixture of white marble and green serpentine
(#132:n132#). This is believed to have been obtained
from some part of Italy, but the quarries are not now
known.
// 118.png
.pn +1
149. Sienna Marble is of close texture, and yellowish
colour, disposed in large irregular spots, surrounded
with veins of bluish red, passing sometimes into purple. It
is not uncommon in the vicinity of Sienna, and is in
great request, throughout Europe, for chimney-pieces
and ornamental furniture.
150. Brocatello Marble is somewhat like the
last; but is also irregularly marked with various shades
of red, and, in some parts, with white.
151. Mandelato Marble is of light red colour, with
yellowish white spots. It is found at Lugezzana, in the
Veronese. Another variety, bearing the same name,
occurs at Preosa.
152. Verde di Prato Marble is a green marble,
marked with darker green spots, which is found near the
town of Prato in Tuscany.
153. Lago Maggiore Marble is a beautiful kind,
white, with black spots and dots. It has been employed
for decorating the interior of many churches in the Milanese.
154. Bretonico Marble.—This beautiful marble,
which is found near the village of Bretonico, in the
Veronese, is varied with yellow, grey, and rose colour.
FRENCH MARBLES.—155. Many valuable kinds
of marble are obtained from different parts of the French
territory.
156. Campan Marble.—Three kinds of marble are
known by this name, all of them procured from immense
quarries at Campan, near Bagnere, in the Pyrenees.
The first, called Green Campan, is of pale sea-green
colour, and exhibits, on its surface, lines of much
deeper green, forming a kind of net-work. The second,
called Isabel Campan, is of delicate rose colour, with undulating
green veins. The third variety, the Red Campan,
is of deep red colour, with veins of still deeper red.
The green variegations in this stone are formed by a
// 119.png
.pn +1
talcy mineral, intermixed with the lime-stone.—The
Campan marble is well adapted for slabs, tables, chimney-pieces,
and other ornamental purposes in the interior
of buildings; but, if exposed to the weather, the
talcose substances perish, and leave hollow spaces which
render its surface rough and uneven.
157. Griotte Marble is of a deep brown colour, with
blood-red oval spots, formed by shells. Its name has been
obtained from its brownish colour, being similar to that
of the cherries that are called by the French griotte.
This marble has, of late, been much used in the decoration
of public monuments, and in splendid furniture,
in France. Some of the ornaments of the Triumphal
Arch of the Carousel are made of it. The department
of Herault is the part of France from which it is obtained.
It sometimes contains large white veins, which
destroy the harmony of the other tints.
158. Marquese Marble.—This, which is obtained
from quarries, near the village of Marquese, between
Calais and Boulogne, is marked with different shades and
variegations of white and brown. Of this marble Buonaparte
commenced a magnificent column on the heights
near the sea, at Boulogne, to commemorate his victories;
but, since his dethronement, the erection of this
structure has been discontinued.
159. Sarencolin Marble is distinguished by exhibiting
large zones, and angular spots of yellow or blood-red
colour. It is found at Sarencolin, in the High Pyrenees.
160. St. Beaume, or Languedoc Marble, is of
light red colour, marked with white and grey zones, formed
by madrepores. The eight columns which adorn the
Triumphal Arch, in the Carousel at Paris, are of this
marble. It is obtained from quarries at St. Beaume, in
the department of Aude.
161. Breccia Marble of the Pyrenees.—One
kind of this marble contains black, grey, and red, middle-sized
spots in a brownish red ground. It admits of
// 120.png
.pn +1
a good polish. Another kind has an orange-yellow-coloured
ground, containing small fragments of snow-white
colour. Both these are found in the Pyrenees.
SPANISH MARBLES.—162. Few countries are
more productive of marble than Spain; and in few countries
are the public monuments and buildings more
profusely decorated with marble. The vault of the
theatre of Toledo is supported by 350 marble columns;
and an ancient mosque at Cordova is ornamented
with 1200 columns, most of which are of Spanish marble.
The palace and church of the Escurial, and many of
the churches in Madrid, are decorated with marbles of
the most beautiful description.
163. White Spanish Marble.—Near Cordova;
at Filabres, three leagues from Almeria, in Grenada;
and in some other parts of Spain, white marble is obtained,
which is susceptible of a good polish, and is well
adapted to the general purposes of sculpture.
164. Seville Marble is a beautiful red variety,
with shining red and white spots and veins. In the vicinity
of Tortosa is found a kind of marble which has a violet
ground, spotted with bright yellow; and near Grenada
a marble of green colour, which somewhat resembles
the celebrated verde antique (#149:n149#).
165. Spanish Breccia.—There are several beautiful
varieties of breccia in Spain. At Riela, in Arragon,
there is one, composed of angular portions or fragments
of black marble, embedded in a reddish yellow base.
The breccia marble of Old Castile is of bright red
colour, dotted with yellow and black, and encloses fragments
of pale yellow, brick-red, deep brown, and blackish
grey colour.
GERMAN MARBLES.—166. Germany abounds
in marbles, and affords many kinds which are remarkable
both for beauty and singularity. Of these the
kind best known is
// 121.png
.pn +1
167. Lumachelli Marble.—This exhibits beautiful
iridescent colours, which are sometimes prismatic internally,
but more commonly of various shades of red or
orange; whence it has also obtained the name of fire
marble. Few kinds of marble are more generally admired
than this. It has a dark ground, and is marked
throughout with the appearance of small whitish shells,
which, in certain parts, refract the most beautiful and
brilliant colours. This marble is cut into the tops and
bottoms of snuff-boxes, and several other ornamental
articles. It is found in veins at Bleyberg, in Carinthia.
168. Many beautiful kinds of marble are obtained
from the island of Sicily, particularly one called Sicilian
jasper, which is red, with stripes like ribbons, white,
red, and sometimes green. Switzerland abounds in
marbles; Portugal, Sweden, and Norway afford
few. In the Russian empire many have been noticed,
particularly among the Uralian mountains. The late
Empress Catharine caused an immense palace to be
built for her favourite Orloff, which is entirely coated,
both inside and outside, with marble. She built the
church of Isaac with marbles of different kinds, on a
vast space, near the statue of Peter the Great, in Petersburgh.
We are at present very imperfectly acquainted
with the marbles of Asia. Dr. Shaw mentions
a red marble obtained from Mount Sinai; and
Mr. Morier, in his journey through Persia, speaks of a
beautiful translucent kind which he calls marble of Tabriz,
and the colours of which are light green, with
veins sometimes of red, sometimes of blue. He says it
is cut into large slabs, some of which he describes to
have measured nine feet in length, and five feet in
breadth.—No account has hitherto been published of
the marbles of Africa.—In the United States of America
many kinds of marble have been discovered, some
of which have been wrought, and polished; but very
imperfect descriptions have yet been given of them.
169. Few countries produce a greater variety of excellent
// 122.png
.pn +1
marbles than the British Islands. Although
these marbles are seldom noticed much beyond the limits
of the districts in which they occur, many of them are
admirably adapted for ornamental purposes; particularly
for slabs and chimney-pieces. It is much to be regretted
that we should send to foreign countries for stones
which, in many instances at least, could certainly be as
well supplied from our own. The following is an enumeration
of a few of the most important kinds.
ENGLISH MARBLES.—170. Petworth Marble,
when cut into slabs, is equal, both in beauty and
quality, to many of the marbles imported from the Continent.
The Earl of Egremont has, at Petworth, several
chimney-pieces formed of it. Much of this marble
was used in the cathedral church of Canterbury. The
pillars, monuments, vaults, pavement, and other parts
of that venerable structure, have been formed of it. The
archbishop’s chair is an entire piece of Petworth marble.
This marble is found in greatest perfection upon an
estate of the Earl of Egremont, at Kirdford. It lies at
the distance of from ten to twenty feet under the surface
of the ground, and in flakes or strata nine or ten inches
in thickness. Petworth marble is also an excellent
stone for walls; and, for paving, it cannot be excelled.
When burned, it also constitutes a valuable
manure, superior, as some farmers imagine, even to
chalk.
171. Purbeck Marble is obtained from the island
of Purbeck, in Dorsetshire. It is of dark colour, and
contains numerous small round shells, which, when it is cut
and polished, mark it with roundish variegations of
brown, dark green, and grey. This marble was formerly
more used than it is at present. Several of the small
columns, and many of the monuments, in the churches
of Dorsetshire, and the adjacent counties, are formed
of it. But it is not so durable as many other kinds.
Wherever it is long exposed to the weather, the surface
cracks, splits off, and becomes defaced.
// 123.png
.pn +1
172. Babbicombe Marble is one of the most beautiful
kinds that is found in any country. It varies in
colour, from light brown to deep red; and large slabs of
it have been obtained that are elegantly and diversely
marked, some in streaks, others in spots, and others in
different coloured shades.
This kind is quarried at Babbicombe, in Torbay, Devonshire,
and is extensively manufactured into chimney-pieces
in the West of England. An attempt was lately
made to introduce it in London; but, from its not being
the production of a foreign country, this has failed
of success.
173. Derbyshire Marble.—There are, in Derbyshire,
several kinds of marble, most of which contain an
abundance of fossil shells, and other remains of marine
animals. At Wetton, near Ashbourne, a beautiful kind
is obtained, of greyish black colour, which contains a vast
number of whitish and very minute shells. This has the
name of bird’s eye marble. Near Monyash a beautiful
variety is found, of a cheerful colour, inclining to brown
red, and full of large marine figures in all directions;
these, when the marble is cut, appear white, and afford
a pleasing contrast.
174. Kendal Marble.—Some varieties of black,
grey, and brown marble, are wrought near Kendal, in
Westmoreland. These somewhat resemble the Derbyshire
marbles; and, like them, are manufactured into
chimney-pieces, and ornamental slabs for houses. Several
of the slabs are found to contain corallines, and the
remains of other marine animals, which vary their appearance
in a very pleasing manner.
The Mona Marble is a species of serpentine intermixed
with white limestone: it has been already described
(#132:n132#).
SCOTTISH MARBLES.—Scotland affords many
valuable and beautiful varieties of marble.
175. Tirie Marble.—Few of the British kinds of
// 124.png
.pn +1
marble have been more admired than that obtained from
Tirie, one of the Western Islands of Scotland. It is of
a reddish, sometimes a delicate rose-coloured tint, and
sometimes white; and is always intermixed with other minerals
which add to its beauty. The most common of
these is of black colour, and called hornblende; the
others are pale green sahlite, blackish brown mica (#123:n123#),
and green chlorite. In some varieties the hornblende is
more abundant than the marble.
176. Assynt Marble.—At Assynt, in Sutherland,
a white marble has been discovered, which is perfectly
solid and pure, and entirely free from blemishes or
stains. Blocks or slabs of it may be cut of almost any
size that can be required. This marble acquires a
smooth surface, but remains of a dead hue; whence, of
course, its uses as an ornamental marble are much circumscribed.
177. Isle of Sky Marble.—There is found in the
Isle of Sky a marble of pure white colour, which appears
capable of yielding large and valuable blocks. Its
fracture is granular and splintery, and its texture fine.
It is harder, heavier, and more compact than the marble
of Carrara (#146:n146#); and is apparently well fitted for all
the purposes of sculpture. But it has the defect of being
very unequally hard. While some parts of the stone
are nearly as easy to work as that of Carrara, other
parts are so hard as to add a charge of near fifty per
cent. to the cost of the working.
178. Sutherland Marble.—Some beautiful specimens
of marble of dark brown colour, veined with
whitish, light red, or light brown, have lately been
brought from the county of Sutherland. These appear
of close texture, are susceptible of a beautiful polish,
and are capable of being wrought into extremely beautiful
slabs for chimney-pieces and other ornamental
purposes.
179. Glen Tilt Marble is of white or grey colour,
// 125.png
.pn +1
and veined or spotted with yellow or green; some specimens
are nearly white. The granulations are peculiarly large;
and, in its aspect and composition, the Glen Tilt has
great general resemblance to the Pentelic marble (#143:n143#).
This marble has of late attracted the notice of the Duke
of Athol, through the suggestion of Dr. Macculloch;
and chimney-pieces of it have since been made. It is
obtained from a valley of the same name in the county
of Perth.
180. Blairgowrie Marble.—A few miles from
Blairgowrie, in Perthshire, there is an excellent granulated
broad-bedded marble, of sugar-loaf texture, and as
white as the finest statuary marble. It may be easily
raised in blocks and in slabs of great size, perfectly free
from blemishes. This marble is supposed to be well
adapted for ornamental architecture, but its large sparry
texture renders it unfit for the sculptor.
181. Glenavon Marble is of white colour, with
large granular concretions, somewhat like spangles, and
as large as the scales of fishes. This is a valuable kind;
but its situation in the forest of Glenavon, on the property
of the Duke of Gordon, is remote and difficult of
access.
182. Ballichulish Marble.—On the north side
of the ferry of Ballichulish, in Lochaber, there is a rock
of marble, of beautiful ash-grey colour, and of a fine, regular,
and uniform grain, which is capable of being
wrought into blocks or slabs of any size, and is susceptible
of a fine polish. This marble is finely sprinkled
throughout with grains and specks of pyrites (#236:n236#),
and with grains and specks of a beautiful lead ore, which
to the eye appears to be rich in silver. If used for ornamental
purposes, it would be a bright and beautiful
metallic marble.
183. Blairmachyldach Marble.—In the bed of
a river, at the farm of Blairmachyldach, about three
miles south of Fort William, is a singular marble, consisting
of a black ground, flowered with white. It is of
// 126.png
.pn +1
fine close grain, but not very hard. The flowering in
it is light, and beautiful, like fine needle-work, or rather
resembling the frosty fret-work upon glass windows, in
a winter morning.
The cutting and polishing of marble appear to have
been performed by the ancients nearly in the same manner
as it is with us. In polishing, the first substance
employed is a sharp, coarse-grained sand. Afterwards
a finer sand is used, then emery (#58:n58#) in different degrees
of fineness. These are followed by a red powder called
tripoli (#119:n119#): and the last polish is given with putty.
184. BLACK MARBLE is a species of limestone, of uniform
black colour, and easily distinguishable, by an excessively
disagreeable smell, which is emitted on rubbing two
pieces of it together, or striking it with a hammer.
Few minerals are susceptible of a more beautiful
polish than this. It is consequently much used for
chimney-pieces, small columns, vases, and other ornamental
work. There are two quarries of black marble
near Bakewell, in Derbyshire: and it is manufactured
to a considerable extent by Messrs. Brown and Co. at
Derby, who have fixed up in their ware-rooms a large
slab of it as a looking-glass.
By the ancients it was much prized. Marcus Scaurus
is said to have ornamented his palace with columns
of black marble, each thirty-eight feet high; and many
of the monuments of ancient Persepolis were executed
in it. M. D’Avejan, Bishop of Alais, used a kind of
black marble for paving the apartments of his palace;
but the friction and heat rendered it so fetid that his
successors were compelled to substitute another species
of stone in its place.—The pavements, however, of many
churches, and of the porticos of several galleries, on the
Continent, are of black marble.
185. CALCAREOUS ALABASTER is a species of limestone
of somewhat whitish or yellowish colour, translucent,
and internally splendent or shining.
It is nearly a pure carbonat of lime; and occurs in masses,
// 127.png
.pn +1
hanging, like immense icicles, from the roofs of lime-stone caverns,
and also coating the sides of such caverns.
The formation of this substance is deserving of notice.
The water which oozes through the crevices of limestone
rocks, becomes strongly impregnated with minute
particles of lime. This water, when it has reached the
roof or side of a cavern, is generally suspended, for a
considerable time, before a drop of sufficient size to fall
by its own weight is formed. In the interval which thus
elapses, some of the particles of lime are separated from
the water, owing to the escape of the carbonic acid (#26:n26#),
and adhere to the roof. In this manner successive particles
are separated, and are attached to each other,
until what is called a stalactite, having somewhat the
appearance of an icicle, is formed. These stalactites
are sometimes solid, having a lamellar structure; sometimes
of a fibrous texture, radiating from the centre
to the circumference, as may be observed when they
are broken; and sometimes hollow. If the water collects
and drops too rapidly to allow time for the formation
of a stalactite, it falls upon the floor, and there
forms an irregular lump of alabaster, which has the
name of stalagmite. In some caverns, the separation of
the calcareous matter takes place both at the roof and
on the floor; and, in course of time, the substance
upon each increasing, they meet, and form pillars,
sometimes of great magnitude.
Caverns of this kind occur in almost every country.
Those of Derbyshire are well known; but the most
celebrated stalactitic cave in the world is that of Antiparos,
in the Grecian Archipelago.
The kind of limestone formed in the above manner
is what the ancients generally denominated alabaster.
It was employed by them for the same purposes as
marble, was cut into tables, columns, vases, and sometimes
even into statues. They also used it in the manufacture
of vases or boxes for containing unguents.
It is supposed to have been a vessel formed of this
stone that is mentioned in the Gospel of St. Matthew,
// 128.png
.pn +1
where it is said there came unto our Saviour “a woman
having an alabaster box of precious ointment.” In
the National Museum at Paris there is a colossal figure
of an Egyptian deity, which is cut in a kind of alabaster
brought from the mountains between the Nile and
the Red Sea.
186. TUFA, or INCRUSTING CARBONAT OF
LIME, is a calcareous substance deposited by such water as
is impregnated with lime.
It clothes, with a stony coat, the smaller branches of trees,
leaves, moss, plants, and other substances; and thus preserves
them from decay, by protecting them from the action of
the atmosphere.
Most of the substances termed by the common people
petrifactions belong to this kind of lime. They are,
however, merely covered with, and by no means converted
into stone.
The dropping well at Knaresborough, in Yorkshire,
is particularly celebrated for them. An overhanging
rock, several yards in depth, has been gradually formed
of the calcareous matter which the water holds in solution;
and, from this rock, it incessantly drops into the
basin below. The persons who have the care of the
place constantly keep these petrified articles for sale.
Even old wigs and hair brooms are subjected to the
powers of the water, to furnish subjects for attraction
to the visitors. There are other springs of this description
in Oxfordshire and Somersetshire, and particularly
at Matlock, in Derbyshire. We are informed that at
Dalton, on the south side of Mendip, the workmen
not unfrequently discover large pieces of oak enveloped
in blocks of stone which are four or five tons in weight.
Blocks of tufa are, in some countries, cut and used for
building stones; and this substance, when burned, becomes
an excellent lime. Pieces of it are sometimes
hollowed, and used as filtering stones.
In the British Museum there is a human skull completely
incrusted with stone, which was found in the
river Tiber.
// 129.png
.pn +1
The warm baths of Hungary are often so thickly
coated at the sides and bottom with tufa, that, during
certain intervals, it actually fills up the tubes and canals
through which they are supplied. The fur in teakettles
is a somewhat similar deposit from water in
boiling.
187. PORTLAND STONE, BATH STONE, KETTON
STONE, are different kinds of limestone; and, of a
texture so hard and compact as to be used in building.
They have their names from the places where they are respectively
found, in Portland Island, near Bath, and at
Ketton, in the county of Rutland.
Of Ketton stone several of the colleges in Cambridge
are built. Its grain has a singular resemblance to the
petrified roe of a fish, whence also it is sometimes
called roestone. The bridges, St. Paul’s Cathedral, the
Monument, and nearly all the buildings of late date in
London, are constructed of Portland stone.
Some of these kinds of stone, when first dug out of
the quarry, are so soft that they are readily worked into
any form which use or ornament may require. This is
owing to the moisture with which they are naturally
impregnated; but when they once become hardened, by
exposure to the sun and air, they are extremely firm
and solid. On the contrary, other kinds of limestone
that are used for buildings imbibe and retain the moisture
of the atmosphere, in consequence of which they
burst or are crumbled by frost.
We are informed that Portland stone was first used
in London in the reign of James the First, that monarch,
by the advice of his architects, having employed
it in the construction of the banquetting house at
Whitehall. After the great fire in London, it was
brought into general use by Sir Christopher Wren.
188. MARL is a combination of clay, silex (#76:n76#), and lime:
and is denominated calcareous, argillaceous, or siliceous, as
the lime, clay, or silex, is most abundant.
The calcareous part of marl is frequently composed
// 130.png
.pn +1
of shells, whence it frequently has the name of shell
marl; and where these are predominant, it affords an
excellent manure for sandy, dry, gravelly, or light
lands. Marl likewise produces very beneficial effects
on mossy and clayey soils; and these effects, where it
has been properly applied, have been observable for
twelve or fourteen years. Some kinds of marl that contain
but a small portion of lime have been successfully
used in the manufacture of earthenware.
This mineral is usually found at the depth of from
five to nine feet beneath the surface of the ground, and
deposited between beds of clay and sand. It is dug out
with spades; and, in the digging of it, in Ireland, the
workmen not unfrequently meet with the horns of deer
and other curious fossils.
The usual mode by which persons, generally unacquainted
with minerals, distinguish this from other clayey
substances, is, to break a small piece of dry marl into a
glass of vinegar. If it be marl it will immediately dissolve
with considerable effervescence; and the briskness of
the effervescence will be in proportion to the quantity
of lime which it contains.
189. FLORENCE MARBLE is a kind of indurated or
hardened marl, and is remarkable for presenting, when polished,
the appearance of ruined edifices or rocks.
This kind of marble is never used in architecture.
Little slabs of it are cut for Mosaic work, and to be
framed like pictures; and the latter, when of considerable
dimensions, are sometimes purchased at a high
price. If held at a distance from the eye, an inexperienced
observer might mistake a slab of Florence
marble for a drawing in bistre. Here, observes a
French writer, we remark a shattered Gothic castle,
there the mouldering fragments of a cathedral; in one
part ruined walls, and in another shattered bastions and
towers. But, when we approach the picture, the illusion
vanishes, and those imaginary figures which, at a
distance, appeared to be so correctly drawn, become
// 131.png
.pn +1
changed into irregular spots, lines, and shades, which
present nothing distinct to the view.
190. Cottam Marble, which, when cut and polished,
also exhibits the appearance of a landscape, is a
kind of compact marl. It has its name from being found
at Cottam, near Bristol.
191. LIAS, or CALP is a kind of limestone of bluish
black, or greyish blue colour, and composed chiefly of lime,
silex (#76:n76#), clay, and oxide of iron (#21:n21#).
This stone, when burned, forms a cement which has
the property of setting very strongly under water. It
has also, of late years, been employed in a manner which
merits particular notice, for the multiplying of copies
of drawings and penmanship. A drawing is made on
prepared paper with a peculiar kind of ink. A slab of
lias, about an inch thick, is then heated; the drawing
is placed upon it, and both are passed through a rolling
press. The paper is afterwards wetted, and washed
from the stone; but the ink, being of a gummy or glutinous
quality, becomes in part absorbed by the stone,
and remains. The stone is then ready for the printer.
Previously to taking off each impression, the stone is
wetted with a sponge; fresh ink (which is said somewhat
to resemble printers’ ink, and is put on with a
ball similar to that used by letter-press printers) is then
applied. This is prevented, by the water, from adhering
to any part except to the ink that had been absorbed,
by the stone, from the paper on which the drawing
was originally made. Paper is then placed on the
stone, both are passed through a rolling press as before,
and a perfect impression of the drawing is made upon
the paper.
This art has been practised in Germany with great
success; and with the difference only of the original
drawing being made upon the stone instead of paper.
Many beautiful specimens of drawings, taken from slabs
of lias, may be seen in this country. It is said that copies
of military drawings and orders were, to a very
// 132.png
.pn +1
large amount, multiplied by this means at the headquarters
of the armies lately employed on the Continent.
An artificial composition is sometimes used instead
of lias.
Considerable quarries of this stone are wrought in
Germany. It is also found at Leixlip, near Dublin;
in beds at Aberthaw, in Glamorganshire; in Dorsetshire,
and near Bath.
SULPHAT OF LIME.
192. ALABASTER, or GYPSUM, is a kind of sulphat
of lime, or of lime in combination with sulphuric acid (#24:n24#),
which has a shivery and glittering texture; and is of white
colour tinged with grey or red, and sometimes striped, veined,
or spotted. When crystallized, the primitive form of its crystals
is a regular four-sided prism (#Pl. II, Fig. 14.:pl-2#)
Being considerably softer than marble, this mineral
is not capable of receiving a good polish. From this
circumstance it is, however, the more easily worked.
It is manufactured into chimney-pieces, columns, busts,
ornamental vases, and lamps; the latter of which transmit
a soft and pleasing light. Such is sometimes the
transparency of alabaster, that it has been employed
for windows; and, at Florence, there is now a church
which receives its light through the medium of this
substance.
The ancients, though acquainted with the art of
making glass, had not attained the knowledge of reducing
it into thin transparent plates; and frequently
employed alabaster for windows. Of this stone the
Temple of Fortune, which was built by order of the
Emperor Nero, was erected. It had no windows whatever,
and received only a soft kind of light through its
walls; appearing rather as if the light issued from the
interior, than that it was admitted from without.
The hot springs of St. Philip, which supply the baths
of Tuscany, are so strongly impregnated with alabaster,
that artists take advantage of this to obtain impressions
of bas-reliefs, by merely exposing their moulds to a
// 133.png
.pn +1
current of the water until they become filled with the
earthy deposit. These impressions, when taken out,
are found to be as hard as marble, and are very beautiful.
There are, in the British Museum, some casts of
medals formed from the water of these springs.
When alabaster is heated, it falls into a soft white
powder, which, on being mixed with water, absorbs it
so rapidly, that if it be formed into a paste, it dries and
becomes hard in a few minutes. In this state it is called
plaster of Paris; and is employed for the making of
statues, casts, and other ornamental work, which,
though of a beautiful white colour, are very brittle.
When mixed with coloured gummy or glutinous substances,
it yields plasters of different hues, and has the
name of stucco; and, in this state, is used for lining the
walls and ceilings of rooms. This plaster is much in
request in the northern counties of England, for the
floors of dairies, store-rooms, granaries, and other
apartments; and, when properly formed, it constitutes
a very smooth and durable flooring.
The fine white varieties of gypsum are used as an
ingredient in the composition of earthenware and porcelain;
and the glaze, or enamel, with which porcelain
is covered, has the purest gypsum for one of its ingredients.
Of late years this mineral has been advantageously
employed as a manure for fertilizing the soil.
Gypsum is found in Cheshire and Derbyshire, as well
as in several parts of the Continent. That which is
imported into this country from Italy and Spain is considered
the best.
193. Fibrous Gypsum.—There is a variety of gypsum
which has a somewhat fibrous appearance, and
which, when cut in a convex form, and polished, reflects
a light not much unlike that of the cats-eye (#86:n86#).
Hence it is sometimes sold to ignorant persons for that
stone. It has also been imposed upon purchasers for
the gem called moonstone (#113:n113#). Fibrous gypsum is
cut into ear-pendants, crosses, beads for necklaces, and
other female ornaments; but its softness is such as to
// 134.png
.pn +1
allow of its being easily injured both by dirt and
friction.
FLUAT OF LIME.
194. FLUOR SPAR, or DERBYSHIRE SPAR, is a
mineral formed by the combination of lime with fluoric acid
(#27:n27#).
It sometimes occurs in a massive, and sometimes in a crystallized
state; the primitive form of its crystals being a regular
octohedron (#Pl. II, Fig. 5:pl-2#). Its colour
is usually bluish, green, yellow,
whitish, or a mixture of some of these.
When heated, this substance cracks, and shines
brightly in the dark. But if kept hot for some time, it
ceases to be luminous, and this property cannot be restored
to it. If also two pieces be rubbed strongly together,
they become luminous in the dark.
From this spar are made several kinds of ornamental
vases of considerable size, columns, and toys, which,
from being extremely varied in their colours and appearance,
and admitting of a high polish, are very
beautiful. When a piece of fluor spar is to be wrought
into a vase, or any similar article, it is first carved with
a mallet and chisel into a somewhat spherical form.
It is then fixed to a turner’s lathe, and, with great care,
is formed into the shape that is required. When this
is complete, it has to be polished, which is done first
with gritstone and pumice (#108:n108#), and lastly with emery
(#58:n58#) and putty. The lathes formerly in use were worked
by the foot; but those now adopted are worked by
machinery, the advantage of the more steady motion of
which has been that ornaments of much more delicate
structure can now be formed than before. The manufacture
of articles from fluor spar gives employment to
a great number of industrious families in Derbyshire.
This mineral occurs in several parts of that county,
where it has the name of Blue John, and where it is
obtained from caverns at a considerable depth beneath
the surface of the earth. It is also found in various
countries both of the European and American continents.
// 135.png
.pn +1
The acid produced from fluor spar is called fluoric
acid (#27:n27#), and has the peculiar property of corroding
glass and flint, and consequently cannot be kept in
glass bottles. Artists, by means of fluoric acid, are
enabled to etch on glass, in the same manner as, with
aqua fortis (nitric acid), they do on copper. The process
is sufficiently simple. The glass is first a little
heated, for the purpose of covering it thinly over
with wax; then, with a needle or other fine point the
drawing is to be made, by cutting through the wax to
the surface of the glass. The edges are next to have a
little wall of wax raised upon them. This done, the
glass must be placed in an horizontal position, and
sifted over with fluor finely pounded; and lastly, a mixture
of one part of spirit of vitriol or sulphuric acid (#24:n24#)
with two or three parts of water is to be poured gently
upon it. The acid will be prevented from running
off by the wax; and, in the course of a little while,
if these be cleared away, the glass will be found corroded
in all the lines along which the needle passed.
The mode of obtaining fluoric acid for chemical purposes
is, by pouring sulphuric acid upon powdered spar
in a leaden retort, and applying to it a gentle heat.
This acid should be used with great caution; for, when
applied to the skin, it instantly disorganizes it, and
produces very painful sores.
.sp 2
.h5
BARYTES FAMILY.
.fs 85%
195. These minerals are sometimes called ponderous
earths, and have their name from a Greek word signifying
heavy. They comprehend all the combinations of barytes with
acids.
When purified, they form a greyish white, porous substance,
which is easily reducible to powder; has no perceptible
smell, but has a harsh and more burning taste than lime, and
changes the blues of vegetable colours to green.
.fs 100%
Although barytes is one of the most useful chemical
tests that we are acquainted with, it is not much employed
in the arts, because, when purified, it is found
too expensive. It is capable of being made into a very
// 136.png
.pn +1
tenacious cement; and painters use a preparation that
is made from it as a white colour which will not
change. This is sold in the shops under the name of
“Hume’s permanent white.” Barytes taken into the
stomach proves a virulent poison; yet a preparation of
it is used in medicine, and particularly for the removal
of scrophulous complaints. When finely pounded and
mixed with oatmeal, carbonat of barytes has been found
an efficacious poison for rats.
196. SULPHAT of BARYTES is a mineral formed by
the combination of sulphuric acid (#24:n24#) with barytes.
It sometimes occurs in a state of powder, frequently in
shapeless masses, and often crystallized: the primitive form of
its crystals being a four-sided prism. It is not soluble in any
other than sulphuric acid.
With us sulphat of barytes is of no use in the arts.
The Chinese, however, employ it as an ingredient in
the composition of porcelain; and it is said to form a
good manure for clover fields.
The Bologna Phosphorus, or Bononian Stone,
a very remarkable kind of barytes, has its name from
being found near Bologna in Italy. This substance,
when detached, is usually observed in roundish, flat,
kidney-shaped pieces, from about the size of a walnut
to that of an orange, which have a shining and somewhat
fibrous texture within.
When the outer coat of this stone is washed away by
heavy rains, it has sometimes the appearance of burnished
silver. An Italian shoemaker, in the year 1630,
deceived by this appearance, carried home several
pieces, hoping, by means of fire, to extract silver from
them. But at the same time that he was disappointed
in this expectation, he was surprised by a very unlooked-for
phenomenon. All the pieces which he had thus
attempted to melt, when they were afterwards exposed
to the light, became themselves luminous. It is the
singular property of the Bologna phosphorus, after it
has undergone calcination in a particular manner, to
// 137.png
.pn +1
become capable of imbibing so much light on exposure,
for a little while, to the light of the sun, or even to the
flame of a candle, that it will afterwards shine in the
dark for an interval of from eight to fifteen minutes,
like a glowing coal, but without any sensible heat. The
light which it emits is sufficient to read by, provided the
letters be placed near it. If well prepared, the stone
will retain this extraordinary property for five or six
years.
The preparation of it is thus conducted. Pieces of
sulphat of barytes are made red hot, for a few minutes,
in a covered crucible placed in the middle of a fire, and
then left to cool. When cool, they are pounded in a
stone mortar, and sifted. The powder thus formed is
made into a paste with a little gum arabic, and divided
into long cakes, or cylinders, each about a quarter of
an inch thick. These pieces are dried in a moderate
heat, and then, by degrees, are exposed to a more
violent heat, among charcoal, in a wind furnace. As
soon as the coals of the furnace are half consumed, it
must be filled a second time, and the phosphorus must
be left undisturbed. When the coals are quite consumed
the ashes must be carefully blown off with a pair of
bellows, and the phosphorus will be found at the bottom
of the grate.
// 138.png
.pn +1
.pb
.sp 4
.h3
CLASS II.—SALTS.
.sp 2
.h4
ORDER I.—EARTHY SALTS.
.hr 10%
.sp 2
.h5
ALUMINE FAMILY.
197. ALUM is a substance of yellowish or greyish white
colour, usually opaque, but sometimes transparent. When
purified, it consists of slender, irregular, hair-shaped fibres,
and has a sweetish, astringent taste.
The alum of commerce is an artificial production
from the different kinds of stones which contain it. That
called Roman alum, from its being procured from the
neighbourhood of Rome, is usually considered preferable
to the other sorts; but good alum of our own manufacture
is equal to it in quality. The Levant, or
Roche alum, is said to have had its name from the village
of Rocca, the present Edessa, in Syria.
There is a famous alum mine at Tolfa, near Civita
Vecchia, in Italy. The alum is obtained from this mine
nearly in a pure state; and it is so extremely hard, that
it can only be wrought by means of pickaxes, and gunpowder.
At Solfatara, near Naples, and in other volcanic
countries, an abundance of alum is found, in a
state of efflorescence, from the lava.
The alum of our own country is manufactured from
a kind of slaty stone which is found near Whitby, in
Yorkshire. This manufactory was first established about
the conclusion of the sixteenth century, by Sir Thomas
Chaloner, who is supposed to have obtained his knowledge
of the process, from the alum works which had
then lately been introduced into Germany and Spain.
The rock of alum slate, near Whitby, is supposed to
be nearly twelve miles in extent: and affords an abundant
supply of alum. The workmen tear open the
// 139.png
.pn +1
rock; after which the different fragments are loosened,
in the form of slaty leaves or plates, that are of a dark
grey colour. To obtain the alum, a bed of fagots is
formed from ten to twelve feet in depth. By the side
of this a scaffold is erected, which enables the workmen
to form a pile of mineral about fifty feet long,
and forty feet high. While this pile is forming, the
fagots are lighted. By the gradual operation of the
heat, a calcination takes place, in consequence of
which the alum is afterwards rendered capable of being
more easily separated than it otherwise would be from
the stone in which it was contained, and from other
extraneous matters that are combined with it. After
this, the mineral is washed in shallow vessels, so arranged
that the water may be poured from one into the
other. By this process the alum becomes suspended in
the water, while all the earthy particles subside to
the bottom. The next operation is to evaporate the
water saturated with alum. This is done by boiling
it in large leaden caldrons, fixed, on cast iron bars,
over a furnace. As soon as the contents of the caldrons
are brought to a proper state, they are drawn
off into casks, where the alum concretes into a mass.
The hoops are then taken off, and the alum is broken
and left to dry; after which it is packed in casks for
sale.
Alum is an article of indispensable importance to
dyers, not only on account of its cleansing and opening
the pores of the substances to be dyed, and thus rendering
them fit to receive the colouring particles, but also
from its more essential property of fixing the colours
in such manner that they cannot afterwards be washed
out. By tanners it is in great request for giving firmness
to the skins after they have been rendered flaccid
in the lime-pits. It is employed in the manufacture of
paper, and by engravers, and other artists. In the
making of candles, alum is added to the tallow, to
render it glossy, and to give it greater firmness and
consistence; and, mixed with cream, it aids the separation
// 140.png
.pn +1
of butter. It has a tendency to retard ignition.
Paper soaked in alum water does not easily take
fire, and is thereby better fitted for the preservation of
gunpowder. Such paper is likewise used in the whitening
of silver, and the silvering of brass. It has been
recommended that ladies’ muslin dresses should be
dipped in a solution of this substance, for the purpose
of rendering them less liable to catch fire. A solution
of alum also retards the putrefaction of animal substances,
and affords useful, as well as economical,
means of preserving natural productions that are imported
from foreign countries. Alum is frequently
mixed with paste, to prevent its losing its tenacity by
the absorption of moisture. It is asserted that bakers
occasionally use it as an ingredient in bread, and that
its presence may be discovered by thrusting a heated
knife into a loaf before it is cold: if free from alum,
scarcely any alteration will be visible on the blade, but
if the contrary, the surface, when cool, will appear
slightly covered with an incrustation of alum. A very
important purpose to which alum may be applied is in
the purifying and sweetening of water that has become
fetid and unfit for use; from five to ten grains of burned
alum, and double or treble that quantity of pounded
charcoal, will correct the fetor of a gallon of water.
Printers’ cushions, and the blocks used for the printing
of calicos, are rubbed with burned alum to remove
any greasiness, which otherwise would prevent the ink
or colour from sticking. This substance is also occasionally
employed by surgeons to stop the bleeding of
small vessels, to corrode fungous or proud flesh, and
for other purposes in medicine.
.sp 2
.h5
198. MAGNESIA FAMILY.
.fs 85%
This is a family of minerals which comprehends all the
combinations of magnesia with acids.
When freed from extraneous matters, magnesia is a powdery
substance of limpid white colour.
.fs 100%
// 141.png
.pn +1
199. EPSOM SALTS, or SULPHAT OF MAGNESIA,
consist of magnesia in conjunction with sulphuric acid
(#24:n24#).
It is said that Epsom salts have been found in the
Alps, and in Switzerland, under a powdery form, and
sometimes even in masses, or a state of incrustation on
stones and rocks. They are, however, chiefly found
dissolved in mineral waters, and particularly in those
at Epsom in Surrey, and Sedlitz in Bohemia. Their
taste is bitter and unpleasant. So little are they affected
by exposure to the air, that the Abbé Haüy kept
some by him for more than twelve years without any
sensible alteration.
These salts are much used in medicine, and are sometimes
manufactured from the waters of Epsom (#290:n290#)
and Sedlitz (#289:n289#), but more frequently, and in much
greater abundance, from sea-water.
The magnesia of the shops is prepared by dissolving
Epsom salts in water, and adding to the solution half
their weight of potash (#205:n205#). The substance that sinks
to the bottom is magnesia; and this, washed with a
sufficient quantity of water and dried, has the appearance
of a light, soft, and white powder, of insipid taste.
Magnesia is used in medicine, both in a simple state
and when calcined or burned. It is also employed in
some chemical processes; and is in considerable request
in the manufacture of enamel and porcelain. If putrid
water be agitated with a small quantity of magnesia, it
will lose a considerable portion of its bad taste and
smell.
.sp 2
.h5
200. SODA FAMILY.
.fs 85%
Soda, like potash (#205:n205#), is an extremely caustic alkali (#42:n42#).
It has a greyish white colour, and agrees exactly with potash
(#205:n205#) in taste, smell, and corrosive quality, but it is not so
heavy.
In a mineral state soda has hitherto been found only in
combination with some acid.
Common salt (#202:n202#) is a compound of soda with muriatic
acid (#29:n29#).
.fs 100%
// 142.png
.pn +1
The soda of commerce is obtained from sea-water;
and from the ashes of different kinds of plants that
grow on the sea-shores, but particularly from that called
salsola soda, which is found in great abundance on the
coasts of the southern parts of Europe; and from which
it has its name. It is sometimes called barilla, from
the salsola soda being so denominated in Spain.
This alkali is of essential use in the arts. When
melted with flint or sand, it forms glass, and answers
much better for this purpose than potash. In conjunction
with oil and lime, it is employed in the manufacture
of soap; and it is used as a substitute for soap in the
cleaning and bleaching of linen, flannels, and worsted
goods. If a weak solution of soda be poured into foul
bottles, or casks in which wine has long been kept, it
will cleanse them. It may also be successfully used
for the cleansing of vessels in which milk has become
acid. Saddles, bridles, or boot-tops, may be effectually
cleaned by means of this liquor, and restored nearly to
their original colour and appearance.
The art of soap-boiling may easily be illustrated by
the following experiment. Take a piece of quick-lime,
slake it gradually by sprinkling on it a sufficient quantity
of water. When it is completely slaked, add to it
about twenty times its weight of water. To this mixture
add two parts, by weight, of common subcarbonat
of soda, previously dissolved in a sufficient quantity of
water. Boil the whole for about half an hour, strain
it through a cloth, and boil it till so much of the water
is evaporated that a phial that will contain an ounce of
water will hold one ounce, seven pennyweights and a
half, of this ley. Then mix in an earthenware pipkin
or basin, one part of the ley, with two parts of olive
oil. Place the mixture in a gentle heat, capable only
of making the liquor simmer, and allow it to simmer,
stirring the liquor continually, with a wooden stick, till,
by letting a few drops of it fall on a plate, the soap will
be found to coagulate, and the water become speedily
separated from it. After which, pour out the contents
// 143.png
.pn +1
into a cup, and suffer it to cool.—Soap may also be
prepared without heat. If one part of the ley be mixed
with two parts of olive oil, in a glass or stone ware vessel,
and the mixture be stirred, from time to time, with
a wooden spoon or spatula, it will become thick, and
white; in seven or eight days afterwards the combination
will be completed, and a white and firm soap will
be obtained.
White soap is formed of ingredients similar to those
that have just been mentioned. Yellow soap is made
with tallow, resin, and soda. Soap may be formed by
boiling shreds of woollen cloth with ley till the whole
has acquired a certain consistence. This kind of soap
has been made, and applied with success, in several
manufactories in France.—The combination of oil and
other ingredients with potash (#205:n205#), instead of soda,
affords what is called soft soap.
201. NATRON, or CARBONAT of SODA, is a salt
which consists of soda (#200:n200#) in combination with carbonic acid
(#26:n26#). It is massive, of greyish colour, soluble in water, and
has a disagreeable alkaline taste.
This salt is found in Egypt, on the surface of the
earth, and particularly near the margins of certain
lakes called natron lakes. In the summer season the
water of these lakes is evaporated by the heat of the
sun, leaving a bed of natron generally about two feet in
thickness. This is broken with wedges and hammers;
and packed up for sale in the European markets. The
waters of some of the lakes contain both common salt
and natron; and these, on evaporation, crystallize in
successive beds. Natron is found in considerable quantity
under the form of an efflorescence, on the surface of
the earth, in the plains of Debreczin in Hungary. It
is likewise found in small quantity in the ashes of most
vegetables, but particularly in those of salsoda and
salicornia.
The ancient Egyptians are said to have made great
use of natron for the preservation of dead bodies, by macerating
// 144.png
.pn +1
them in it for several months previously to their
being embalmed. Large quantities of this salt are
sometimes imported into England, by the East India
Company’s ships, from China, and other parts of the
East. It is employed in the manufacture of soap, and
for the washing of linen. Glass-makers mix it with sand
for the formation of glass. On the continent it is administered
as a medicine in complaints of the bowels
and liver. The ancients sometimes employed a mixture
of natron for soaking their seed corn, under an impression,
that, when afterwards committed to the earth, it
would thereby be rendered more fertile.
202. COMMON SALT, or MURIAT of SODA, though
found in some countries in a solid and massive state, is for the
most part an artificial preparation from sea-water, and from
the water of salt lakes and brine springs. It consists of soda
(#200:n200#) in combination with muriatic acid (#29:n29#).
Few productions, either natural or artificial, are in
so much request as common salt. It is used by the inhabitants
of nearly all countries, for correcting the insipidity
of food. When applied in small quantities, it accelerates
the putrid fermentation; and, in this case, is considered
to aid digestion, by promoting the decomposition
of the aliments. In larger quantity it has a contrary
effect, and tends to preserve organic substances from
corruption. Salt is used for glazing the surface of
coarse earthenware; and is employed in several processes
of dyeing.
When this substance is dug out of the earth it has the
appellation of rock salt: and immense masses of it are
found in different countries of the world. The most
considerable, as well as the most celebrated salt mines,
with which we are acquainted, are those about five
miles from Cracow, in Poland; and it is supposed that
they contain more salt than would be sufficient to supply
the wants of the whole world for several thousand
years. On descending to the bottom of these mines,
a stranger is astonished to find a kind of subterraneous
// 145.png
.pn +1
republic, consisting of many families, who have their
own peculiar laws and polity. Here are likewise public
roads, and carriages, horses being employed to draw
the salt to the mouths of the mine, where it is taken up
by engines. The horses, when once they are down,
never more see the light of day; and many of the people
seem buried alive in this immense abyss. Some are
born there, and never stir out; others, however, have
occasional opportunities of breathing the fresh air in
the fields, and enjoying the light of the sun. The subterraneous
passages or galleries are very spacious; and,
in many of them, chapels are hewn out of the salt. In
these are set up crucifixes, and the images of saints, before
which lights are kept continually burning. In some
parts of the mine huge columns of salt are left standing
to support the rock. Its windings are so numerous and
intricate, that workmen have frequently lost their way:
the lights they carried have been burned out, and they
have perished before they could be found. The salt is
taken from these mines in blocks so large as, sometimes,
to measure nine feet in length, four feet in width, and
two or three feet in thickness. In the year 1780, the
greatest depth to which the workmen had penetrated
was about 320 yards, and the mass of salt was considered
to be in some places more than 240 yards thick,
and to extend at least three leagues.
Near the town of Cardona, about fifty miles northwest
of Barcelona, in Spain, there is a mountain of salt,
without cleft or crevice, 500 feet high, and nearly
three miles in circumference. In the province of Lahore,
in Hindostan, travellers have described a mountain
of the same mineral, not inferior to this in magnitude;
and the elevated regions of Peru afford rock salt
at the height of 7000 feet above the level of the sea.
At Northwich and Nantwich, in the county of Chester,
there are salt mines of great depth and extent.
These are frequently visited by travellers, and are found
amply to repay the trouble and inconvenience of descending
into them. There are two principal beds of
// 146.png
.pn +1
this substance; the upper one is about forty-two yards
below the surface, and twenty-six yards thick. This
was originally discovered about a century and a half ago,
in searching for coal. The lower bed has already been
examined to the depth of forty yards, without coming
to the bottom; and it is about the centre of this bed
that the purest salt has been discovered. The average
depth of the cavity, formed by the workmen along the
vein of salt in the different mines, is supposed to be
about sixteen feet. In some of the mines, where pillars
six or eight yards square are left to support the
roof, the appearance of the cavity is singularly beautiful:
and the effect is greatly increased when the mine
is illuminated by numerous candles fixed to the side of
the rock. The scene so formed would almost seem to
realize the notion of the magic palaces of Eastern poets.
Some of the mines are worked in aisles or streets. The
methods employed in working out the salt offer nothing
worthy of notice. Larger masses are separated from the
body of the rock, by blasting with gunpowder; and
are afterwards broken down with pickaxes, hammers, and
other instruments. The present number of mines in the
vicinity of Northwich is eleven or twelve, from which
there are raised, on an average, 50,000 or 60,000 tons
of salt per annum. The greater part of this quantity is
exported to Ireland and the Baltic; and the remainder
is employed in Cheshire, and the adjacent counties.
Salt is also made from brine springs in Cheshire,
Cumberland, Staffordshire, and Worcestershire; but
the kind most commonly used in England is that which
is made from sea water, and has the name of sea salt.
The mode of manufacturing it is very simple. The
water is first pumped into shallow reservoirs of earth,
called salt pans, or salterns. In these it remains exposed
to the sun until a certain proportion of the water
is evaporated, so as to leave it about seven times stronger
than in its original state. It is then conducted by another
pump into flat iron pans, eight or nine feet square,
and as many inches deep. These, being placed over a
// 147.png
.pn +1
hot fire, the liquor or brine is boiled until nearly all the
remaining particles of water have passed off by evaporation,
and nothing is left in the pans but salt. This is
thrown together into proper vessels, for a few days, to
drain, after which it is fit for use.
In some countries the whole evaporation is performed
by the heat of the sun; and, in extreme northern climates,
where the sun would not have sufficient power
for the operation, a very different process is adopted.
The water is suffered to freeze in the salterns, and that
portion of it which continues uncongealed is so strongly
saturated that it requires only a moderate heat to evaporate
the remainder of the water, and to crystallize
the salt.
Bay salt is that which is produced from the evaporation
of sea-water by the heat of the sun only.
The inhabitants of Cardona, in Spain, make of the
rock salt in their neighbourhood various transparent articles,
which they vend at a cheap rate. These, which
consist of small altars, figures of saints, crosses, chandeliers,
salt-cellars, &c. are as clear as crystal, and, to appearance,
as lasting. They are chiefly purchased by
strangers as curiosities, and are distributed over various
parts of Spain and the south of France.
The decomposition of salt furnishes the muriatic acid
(#29:n29#), or spirit of salt of commerce. This liquid, which
is much used in the arts, and is in great request by
chemists, is prepared, for common purposes, by mixing
one part of common salt with seven or eight parts of
clay, and distilling the mixture; or by distilling common
salt and spirit of vitriol or sulphuric acid (#24:n24#), and
receiving the product into a vessel containing water.
It has been discovered that muriatic acid, in a state
of gas, is an excellent means of correcting putrid exhalations.
In the year 1773, the cathedral church of Dijon
was so much infected by the corruption of bodies
which had been interred within its walls, that it was entirely
deserted. The professor of Chemistry at Dijon
having been applied to for assistance, placed, on a few
// 148.png
.pn +1
burning coals, in the middle of the church, a glass vessel
containing six pounds of common salt. Upon this he
poured two pounds of sulphuric acid (#24:n24#), precipitately
withdrew, and shut all the doors. The gas soon filled
the whole cathedral. After twelve hours the doors were
thrown open, and a current of air was made to pass
through to remove the gas, which had entirely destroyed
every putrid odour.
The following has been recommended as an eligible
mode of fumigating rooms for the prevention of infectious
disorders. Take six drachms of powdered nitre
(#206:n206#), and six drachms of sulphuric acid (spirit of vitriol);
and mix them in a tea-cup, by adding to the nitre
one drachm at a time of the oil. During the preparation
the cup must be placed on a piece of heated iron,
and the mixture stirred with a tobacco pipe or piece of
glass. As soon as the fumes arise, the cup must be
moved about to different parts of the room or house
that are to be fumigated.
203. GLAUBER SALT, or SULPHAT of SODA, is
a salt which consists of soda (#200:n200#) in combination with sulphuric
acid (#24:n24#). It occurs in an efflorescent or powdery state, on the
borders of salt lakes; or, more commonly, in a state of solution,
in certain mineral waters.
This salt, which was originally discovered by a German
chemist whose name was Glauber, has a nauseously
bitter and saline taste. It is found, in an efflorescent
state, on meadow ground at Eger, in Bohemia; and on
the walls of old galleries in mines, at Grenoble, in
France. It is also abundant in the ashes of some kinds
of vegetables, especially of sea weeds. The waters of
the Mediterranean yield a great proportion of it; and
the Glauber salt used for commercial purposes is chiefly
prepared from sea-water, or by decomposing common
salt, in order to procure muriatic acid (#29:n29#). It may
also be obtained by saturating soda with sulphuric acid
(#24:n24#).
The use of this salt in medicine is well known; and,
in some countries, it is employed as a substitute for soda
// 149.png
.pn +1
(#200:n200#), in the manufacture of white glass. It ought to
be kept in well-corked bottles, as otherwise the crystals
soon fall into powder.
The following is a pleasing experiment, which shows
a singular and almost instantaneous crystallization of
Glauber’s salt. Dissolve this salt by adding portions of
it gradually to water kept boiling until the water will
dissolve no more. Pour the solution, whilst boiling,
into common medicine phials previously warmed, and
immediately cork them. Set the phials in a quiet place
without shaking them. The solution, when cool, will remain
perfectly fluid till the cork is taken out; but the
moment this is done, and the air is admitted, it will begin
to crystallize on its upper surface, in fine satin-like
crystals, which will shoot downward, like a dense white
cloud. In this act so much heat becomes evolved as to
make the phial feel sensibly warm to the hand. When
the crystallization is complete, the whole mass generally
becomes so solid, that, on inverting the bottle, not a
drop of it will fall out. If the crystallization should not
immediately ensue on opening the phial, this may instantly
be effected by dropping into it a minute crystal
of the same salt. The experiment may be exhibited
any number of times afterwards, by merely placing the
phial in boiling water, till the salt it contains be again
completely liquefied; and letting it stand, as before, to
cool.
204. BORAX is a salt composed of boracic acid (#28:n28#) and
soda (#200:n200#), and is imported chiefly from the East Indies, in
the form of a brownish grey, impure, shapeless salt, of sweetish
taste; or in detached prismatic crystals, each about an inch in
length.
Although borax has long been known as an article of
traffic, there is scarcely any production with the origin of
which we have been, till lately, less acquainted. It is
found in a native, though impure state, in a mountain
lake, situated about fifteen days’ journey from the capital
of Thibet in the East Indies. This lake is so encompassed
with hills as to have no stream either falling into
// 150.png
.pn +1
it or flowing from it. The water is salt to the taste, and
contains both borax and common salt; and the edges
and shallow parts are covered with a stratum of this
substance, which is dug up in considerable masses for
exportation. It has here the name of tinkal, and is
usually brought into Europe enveloped in a kind of fatty
substance. The mode of refining it was for a long time
kept, by the Dutch and Venetians, amongst those secrets
which a want of sufficient research alone prevented
from being generally known. When refined, it is called
borax.
The uses of borax are numerous. It is employed as a
flux for metals, being found to produce a more perfectly
limpid fusion than any other substance. For the same
reason it is made an ingredient in the finest kinds of glass,
and particularly in some of the coloured glass pastes
which are manufactured in imitation of gems. But its chief
use is to jewellers and goldsmiths, to facilitate the soldering
of gold and silver. Borax is also used in medicine.
.sp 2
.h5
205. POTASH FAMILY.
.fs 85%
Potash is an alkaline substance (#42:n42#), of white colour, and
of smell somewhat resembling that which is perceived during
the slaking of quick-lime (#137:n137#). It is extremely corrosive,
and remarkably acrid to the taste.
In a mineral state it is found only in combination with nitric
acid (#30:n30#).
.fs 100%
Potash principally exists under the form of a salt, in
vegetable substances; and is obtained by burning them,
afterwards repeatedly washing the ashes with water, and
then filtering and evaporating these to dryness. The
appellation of potash was given to this salt from its having
formerly been prepared in large iron pots.
The uses to which it is applied are numerous. In
chemistry it is employed for a variety of purposes; and
also in many arts and manufactures, in scouring, washing,
bleaching, dyeing, glass-making, and several others.
Its corrosive property is such that it is often used by
// 151.png
.pn +1
surgeons under the name of potential cautery, to open
abscesses, and to destroy useless or hurtful excrescences.
Potash, after it has been made red hot, is rendered
whiter and more pure. In this state it has the name of
pearl ash.
206. NITRE, or SALTPETRE, is a salt which consists
of potash in combination with nitric acid (#30:n30#).
Its colour is whitish or limpid; and it does not liquefy by the
action of the air. It is usually observed in the form of fine
capillary crystals, though it is sometimes found in a massive
state. When pure, it crystallizes into six-sided prisms
(#Pl. II, Fig. 15:pl-2#) which have a rectangular base.
It is denominated by chemists nitrat of potash.
Nitre is found incrusted on the surface of the
earth, in some parts of India, Africa, and Spain, and,
in such abundance, as to admit of being swept off
at certain seasons of the year, twice or three times a
week. In our own country it not unfrequently occurs
in a state of white efflorescence, on old plaster walls
that are sheltered from rain. Nitre is also produced in
stables and cart-houses, from the mixture of animal and
vegetable substances in a state of putrescence.
Many kinds of plants, which grow in soils favourable
to the production of it, contain nitre: this is particularly
the case with pellitory, borage, and the large
sunflower.
Immense quantities of nitre are annually required for
the purposes of war. From its constituting one of the
most important substances in the composition of gunpowder,
it has been found necessary to adopt artificial
modes of procuring it. In several districts of the East
Indies there are places called saltpetre grounds. From
these large quantities of the earth are dug, and put into
cavities through which water is passed. This brings
away with it the salt which the earth contains, and which
is afterwards separated from the water by boiling. The
East India Company, for more than a century past, has
been under engagements to import into this country, and
supply the board of ordnance, for his Majesty’s service,
// 152.png
.pn +1
with 500 tons of nitre annually, at given rates and prices
in times of peace and war.
In France this article is obtained in what are called
nitrières, or nitre beds. These consist of the refuse of
animal and vegetable substances, which undergo putrefaction,
mixed with calcareous and other earths; and
the nitre is obtained from them by water, as above-mentioned.—The
principal requisites for the formation
of nitre are said to be lime, animal and vegetable matters,
heat, and an open, but not too free communication
with dry atmospheric air.
The discovery of gunpowder has completely changed
the modern art of war. The earliest notice that has
occurred respecting the use of this article in Europe is,
that it was employed in the wars of Germany, somewhat
before the year 1373. It is said, however, to have
been known in China long anterior to that period. Its
component parts are nitre, charcoal, and sulphur, in
the proportion of seventy-six, fifteen, and nine parts, in
every hundred. These ingredients are first reduced to
a fine powder separately, and then mixed with water, so
as to form a thick paste. After this has dried a little, it
is placed upon a kind of sieve full of small holes, through
which it is forced. By this process it is divided into
grains, the size of which depend of course upon the size
of the holes through which it has been squeezed. It
afterwards undergoes some other operations before it is
ready for use.
Nitre is frequently administered in medicine; and it
is used very extensively in different arts. A mixture of
equal parts of nitre and tartar, burned together in a
crucible, forms what is called white flux, which is used
for melting and reducing different kinds of metallic substances.
And a mixture of one part of nitre and two
parts of tartar burned in the same manner forms what is
called black flux. Nitre possesses antiseptic qualities in
a considerable degree, whence it is much used, in conjunction
with common salt and bay salt, for the preserving
of animal food from putrefaction.
// 153.png
.pn +1
Aqua-fortis, or nitric acid (#30:n30#) as it is denominated by
chemists, is prepared from this mineral. The mode of
obtaining it in large manufactories is by distilling a
mixture of nitre and clay in glass or stone retorts, each
capable of containing seventy or eighty pounds’ weight
of this mixture. But the acid thus procured being weak
and impure, chemists, for nicer purposes, generally prepare
it by distilling, in a glass apparatus, a proportion of
three parts of nitre and one of sulphuric acid (#24:n24#). The
uses of aqua-fortis are various and important. All kinds
of metals, except gold and platina, are capable of being
dissolved in it. Hence, among other uses, it is employed
by dyers, for dissolving tin, and forming with
madder a scarlet colour; and, by hatters, for dissolving
mercury (#228:n228#) for some processes in the preparation of
hats. Jewellers use it for several purposes.
.sp 2
.h5
AMMONIA FAMILY.
207. SAL-AMMONIAC, or MURIAT OF AMMONIA,
is a salt compounded of ammonia and muriatic acid (#22:n22#). It is
occasionally found in a state of powder, sometimes in a massive
form, and sometimes in very irregularly shaped crystals, the
primitive form of which is an octohedron (#Pl II, Fig. 5:pl-2#). It is, however,
more frequently an artificial production from the soot of
burned animal matter.
The name of sal-ammoniac was acquired by this substance
from its having been found by the ancients in
great abundance amongst sand near the temple of Jupiter
Ammon, in Africa. It is at present found in Persia;
and, accompanying sulphur, amongst volcanic
matter near Mount Vesuvius.
This salt was formerly imported from Egypt in the
form of conical loaves, or of round cakes, which were
convex on one side and concave on the other; but it is
now made in Europe, by burning at the same time soot,
bones, oil, and salt. The deposit formed by the vapour
consists of sal-ammoniac, in conjunction with other substances,
which are separated from it by a subsequent
process. When good, it is white, transparent, and dry
// 154.png
.pn +1
within; and externally of yellowish grey, or blackish
colour.
Sal-ammoniac is applied to many useful purposes.
Occasionally it is used in medicine. A considerable
portion of it is consumed by dyers, to give brightness
to some of their colours. It is also employed in the
assay of metals, to discover the presence of iron; and
having the property of rendering lead brittle, is sometimes
used in the manufacture of shot. By coppersmiths
and tinners it is used for cleansing the surface of
the metals which they are about to cover with tin. In
certain manufactories sal-ammoniac is mixed with tobacco,
to give that article, or the snuff that is made from
it, additional stimulant properties. Sal-ammoniac dissolved
in nitric acid (#30:n30#) forms the fluid named aqua-regia,
which is employed in the solution of gold.
.sp 2
.pb
.sp 4
.h4
ORDER II.—METALLIC SALTS.
.sp 2
.h5
SALTS OF IRON.
208. GREEN VITRIOL, IRON VITRIOL, or
COPPERAS, is a mineral salt formed on a decomposition of
pyrites (#236:n236#) by the moisture of the atmosphere. It is also called
SULPHAT OF IRON.
Its colour is bright green, and its taste very astringent; a
solution of it in water dropped on oak bark instantly produces
a black spot.
Although copperas is occasionally found in grottoes,
caverns, the galleries of mines, and other places; yet,
being much in request by dyers, tanners, and the manufacturers
of ink, it is artificially prepared from pyrites.
This mineral being moistened and exposed to the air,
a crust is formed upon it, which is afterwards dissolved
in water; and from this the crystals of vitriol are obtained
by evaporation.
// 155.png
.pn +1
The principal use of vitriol is in dyeing woollen articles,
hats, and other manufactures, black. It is the
basis of ink, and is used in the manufacture of Prussian
blue. If it be reduced to powder by the action of fire
in a crucible, and mixed with powder of galls, it forms
a dry portable ink. Sulphuric acid (#24:n24#) may be obtained
from this kind of vitriol by distillation. The residue,
after the process is completed, is used as a red
paint; and when washed, is employed for the polishing
of steel.
.h5
SALTS OF COPPER.
209. BLUE VITRIOL, or SULPHAT OF COPPER,
is a blue salt formed by a combination of copper with sulphuric
acid (#24:n24#).
This substance, though sometimes found in a state of
concretion, or in the form of powder disseminated over
the surface of stones that have been in contact with
water impregnated with it, is more frequently an artificial
preparation obtained from evaporating the water
which runs through copper mines. In the mines of
Neussol, in Hungary, at the depth of 380 feet beneath
the surface of the ground, are several vats, placed at different
distances, for the purpose of collecting the water
impregnated with copper, and which flows into them
through a kind of gallery above. From this water the
vitriol is afterwards separated by evaporation. A process
somewhat similar is pursued in our own country.
In the principal blue vitriol manufactories established
in France, the operation is thus carried on. Pieces of
copper are first dipped into water, and their surface,
while wet, is covered with a stratum of powdered sulphur.
The copper thus prepared is put into an oven,
and heated to redness. After some time, it is taken out,
and, while hot, is plunged into a vessel filled with water.
These operations are repeated several times, till the
whole of the copper is dissolved, and the water becomes
loaded with vitriol. Thus saturated, the water is placed
// 156.png
.pn +1
over a fire till all the fluid particles are dissipated, and
the vitriol alone is left.
Blue vitriol is used by artists and manufacturers in
various ways. It is employed in dyeing: and enters
into the composition of black colours, to which it gives
depth and solidity. Blue feathers are stained by plunging
them into a hot solution of it. The beautiful grass-green
colour of the shops, called mineral green, is made
from blue vitriol; and fowling-pieces and tea-urns are
browned by washing them with a preparation of it.
.h5
SALTS OF ZINC.
210. WHITE VITRIOL, or SULPHAT OF ZINC, is
a whitish, yellowish, or greenish white salt, formed by a combination
of zinc (#241:n241#) with sulphuric acid (#24:n24#).
Although the white vitriol that is used in commerce
is chiefly an artificial preparation, this salt sometimes
occurs in a natural state, in mineral repositories that
contain blende (#241:n241#); and it appears to be formed by a
decomposition of that ore. It is found at Holywell, in
Flintshire, and in some parts of Cornwall.
When white vitriol is artificially prepared, the blende
is roasted, and thrown, while red hot, into a vessel filled
with water; in which it is allowed to remain about
eighteen hours. This process is repeated several times;
and, after the solution has become clear, it is removed
into leaden vessels, and the water is evaporated by
means of heat. On cooling, it crystallizes. After this
the crystals are melted in a copper vessel, and the surface
of the solution is skimmed with a hair sieve. It is
then poured into a wooden vessel, and stirred till it becomes
cool, and acquires a sufficient degree of consistence,
when it is formed into loaves for sale. In this
state it has the appearance and colour of refined sugar.
White vitriol is chiefly manufactured in Germany.
It is used in medicine; and is employed in great
quantities by varnishers, to make their oil varnishes
dry more readily than they otherwise would. A fine
white colour, called zinc-white, which is more durable
// 157.png
.pn +1
than white lead, is prepared from it. Dyers use a considerable
quantity of white vitriol to render deeper the
colours produced by madder, cochineal, and other substances.
A pleasing experiment is made by mixing in a phial
a small quantity of solution of white vitriol with a little
liquid ammonia. Though each of the fluids is transparent
when separate, yet the zinc will now be immediately
precipitated in a white mass; and, what is peculiarly
deserving of remark, if then shaken, it will almost as
instantly be re-dissolved.
// 158.png
.sp 2
.pb
.pn +1
.sp 4
.h3
CLASS III.—COMBUSTIBLES.
.hr 10%
.sp 2
.h4
SULPHUR FAMILY.
211. COMMON SULPHUR, or BRIMSTONE, is a
yellow, dry, and brittle substance, which, in burning, yields a
suffocating fume: the smell of this, under the denomination of
sulphureous, is well known.
Sulphur is found in a pure or native state in nearly all volcanic
countries: it is about twice as heavy as water; and is
sometimes crystallized in the form of octohedrons, whose bases
are rhombs. It exists abundantly in a state of combination
with several metallic substances, and is also formed in putrid
animal remains.
A great proportion of the sulphur which is used in
commerce is obtained by the process of roasting copper,
and other ores, previously to their being smelted. It
passes off in the form of vapour, and, on being received
into chambers constructed for the purpose, is there deposited
in a powdery state. The substance thus formed
is the flour of sulphur of the shops. It is afterwards
melted in large pans, and cast in wooden tubes, to make
the hard, or roll brimstone. Nearly all the sulphur used
in France comes from the Solfatara of Italy. This volcanic
country every where exhibits indications of the
agency of subterraneous fires. Nearly the whole ground
is bare and white; and, in every part, is warmer than the
atmosphere during the greatest heat of summer. A sulphureous
vapour is constantly emitted from the earth,
and sulphur is condensed in various parts, and in great
abundance. This is collected, packed in casks, and
exported to Marseilles, where it undergoes certain preparations
that are necessary towards purifying and
rendering it fit for sale.
A considerable quantity of sulphur is employed in the
// 159.png
.pn +1
composition of gunpowder (#206:n206#). Its readiness of
taking fire is the reason of its being employed in the
making of matches. Sulphur gives a blue colour to artificial
fire-works. Its vapour is used for the whitening
of silk and wool, and also for the bleaching of straw
used for making ladies’ hats.
Modellers employ sulphur to make moulds for various
kinds of casts; and artists are enabled, by means of it,
to take sharp and beautiful impressions of medals
and engraved stones. The mode of doing this is very
simple. The sulphur is put into an earthen vessel called
a crucible, and placed on a hot fire. It soon melts;
and if kept some time over the fire, becomes thick and
dark-coloured. When poured into water in this state,
it is as soft as wax. It may now be easily worked between
the fingers into any given form: and, if pressed
upon a seal or engraved stone, will be found to retain a
perfect impression of it. It is this property of sulphur
of which Mr. Tassie, of Leicester-fields, London, has
availed himself, to furnish extremely elegant impressions
of many antique gems.
Sulphur was much used by the ancients in medicine;
and it is now occasionally administered both as an external
and internal remedy. The compounds formed
from it are employed to considerable extent in various
processes of dyeing and calico printing. Many of the
mineral waters, those, for instance, of Harrowgate (#299:n299#)
and Moffat (#300:n300#), are indebted to sulphur for their
most valuable qualities.
This substance has the property of becoming electric
by rubbing. On exposure to a gentle heat, it melts; but
if the heat be increased, it is entirely consumed, and
passes off in vapour. When ignited, and the combustion
is slow, it burns with a suffocating and acid fume,
and blue flame; but when the combustion is quick it
burns with a white and vivid flame. If exposed to a
sudden, though gentle heat, by holding it, for instance,
in a hand when that is warm, it will sometimes break in
pieces with a crackling noise.
// 160.png
.pn +1
It is a remarkable circumstance, that, if a bar of iron
be heated to perfect whiteness, and then touched with
a roll of sulphur, the two bodies combine, and drop
down together, in a fluid state, forming what is called
sulphuret of iron, a compound of the same nature as
iron pyrites (#236:n236#). A piece of iron rolled out very thin
may be apparently melted in the hand, by putting it,
when heated to whiteness, upon a thick piece of solid
sulphur. It is, however, necessary, that this experiment
be performed with great care; and under a chimney,
or in a place where there is a current of air, to
carry off the suffocating vapour.
Useful as sulphur is, in various ways, its most important
application is supposed to be for the production of
sulphuric acid, or spirit of vitriol (#24:n24#). One mode in
which this acid is obtained for the purposes of commerce,
is by burning a mixture of sulphur and nitre
(#206:n206#) in large chambers lined with lead. In this process
the nitre supplies a considerable portion of oxygen
(#21:n21#) to the sulphur, and the air of the atmosphere furnishes
the rest. Thus a substance which, in a natural
state, is one of the mildest that we are acquainted with,
is by this operation converted into a corrosive and dangerous,
though useful fluid. Its taste is strongly acid:
and, when applied to animal or vegetable substances, it
soon corrodes, and destroys their texture.
The properties of sulphuric acid have rendered it extremely
valuable for numerous purposes, both in the
arts and in the laboratory. It has been long employed by
chemists, as one of their most useful and frequent agents.
The fluid that is put into the bottles for procuring
instantaneous light is no other than sulphuric acid; and
it is poured among filaments of asbestos (which it will
not corrode), for the same purpose as ink is sometimes
poured upon cotton. The matches are slips of wood
dipped in a mixture of equal weights of sugar or charcoal
powder, and what the chemists call hyperoxy-muriat
of potash. These are to be rubbed together in
a mortar, but with great care, as by strong friction the
// 161.png
.pn +1
mixture is apt to explode. To obtain a light, nothing
farther is requisite than to dip a match, thus formed,
into a bottle containing the acid.
.sp 2
.h4
BITUMEN FAMILY.
212. NAPHTHA, or ROCK OIL, is a yellow or brownish
bituminous fluid, of strong penetrating odour, somewhat greasy
to the touch, and so light as to float even on spirit of wine.
By exposure to the air, the consistence of naphtha is increased,
and it passes into petroleum (#213:n213#).
There are copious springs of naphtha at Baku, on
the shore of the Caspian Sea; and also in some parts of
Italy, particularly at Monte-Chiaro, near Piacenza. At
Pitchford, in Shropshire, extensive strata or beds of
sandstone are saturated with this mineral fluid, which is
obtained from the stone by distillation, and is sold, as a
remedy against sprains and rheumatism, under the name
of Betton’s British oil.
By the Persians and Russians naphtha is used internally
as a cordial. On the shores of the Caspian it is
burned in lamps, instead of oil; and, in some parts of
Italy it is employed in the lighting of churches and
streets. When mixed with certain vegetable oils, it
forms an excellent varnish.
It is the property of naphtha to take fire on the approach
of a light, and to burn with great readiness and
a white flame, leaving scarcely any residuum. The
town of Broseley, in Shropshire, was formerly celebrated
for a burning spring, which was first discovered in the
month of June, 1711. Its original issuing from the
ground was announced by a terrible noise in the night,
which awakened several persons who lived near the spot.
Some of these, on going out to ascertain the cause of
the alarm, perceived, about two hundred yards from the
river Severn, an extraordinary shaking of the earth, and
a little bubbling of water through the grass. On digging
round the spot, the water sprang up to a great height,
and a candle which one of them held in his hand, set it
on fire. This circumstance excited great curiosity; and
// 162.png
.pn +1
many persons, from different parts of the adjacent
country, came to visit what was called the “burning
well.” To prevent this spring from being destroyed,
an iron cistern was placed upon it, with a small hole
in the cover, through which the water might be viewed.
When a lighted candle was put into this hole, the water
immediately took fire, darting and flashing in a violent
manner, much in the same way as spirits do in a lamp,
but with greater agitation. It would sometimes burn
for forty-eight hours successively, and without any
sensible diminution: and a tea-kettle, full of water, by
being placed upon the hole, has been made to boil in
nine minutes. In 1747, this spring had been lost for
many years; but another was shortly afterwards discovered,
the issuing of which was announced by a
rumbling noise under ground, similar to that which
had been formerly heard. This, however, also disappeared
in the year 1756, by the sinking of a coal-pit in
the neighbourhood.
213. PETROLEUM, or MINERAL OIL, is a fluid
bitumen, of somewhat greater consistency than naphtha: of
black, brown, or sometimes dingy green colour.
By exposure to the air it assumes the consistence of tar, and
is then called MINERAL TAR (#214:n214#).
This substance exudes spontaneously from the earth,
or from clefts of rocks, and is found in nearly all countries,
particularly in the East Indies, Italy, France,
Spain, Germany, and England. In the neighbourhood
of Rangoon, in Pegu, there are several hundred wells of
petroleum. These are of square form, of considerable
depth, and each lined with cassia wood staves. The oil
is drawn from them pure, and in a liquid state, and is
conveyed thence in small jars. The whole annual produce
of this district is estimated at more than 400,000
hogsheads.
At Colebrook Dale, in Shropshire, there is a spring
of petroleum. This was discovered at the depth of
about thirty yards beneath the surface of the earth, in
digging an archway for the conveying of coals from a
// 163.png
.pn +1
very deep pit. The petroleum was at first found to ooze
from between the crannies of the rock, but it soon afterwards
poured forth in a considerable stream. The
utility of this fluid having been made known, large iron
pipes were formed from the spring into pits sunk for the
purpose of receiving it. From these pits it is conveyed
into immense caldrons, where it is boiled until it attains
the consistency of pitch. Since the first discovery of
this substance, three different springs of it have broken
out. One of these is near the celebrated iron bridge;
and the fluid that issues from it is almost pellucid, but,
at the same time, is thicker than treacle.
Petroleum easily takes fire, and, in burning, yields a
strong, sharp, and somewhat unpleasant odour; and a
thick and disagreeable smoke. In cold weather it congeals
in the open air.
In Pegu, and other parts of the East, petroleum is
used in place of oil for lamps. Boiled with a species
of resin, it is employed for painting the timber of
houses, and covering the bottoms of boats and other
vessels. In the latter respect it is considered to be
particularly efficacious, by protecting the timber from
the attacks of marine worms. It is also used by the
inhabitants of eastern countries as a lotion in cutaneous
eruptions, and as an embrocation in bruises and rheumatic
affections. The ancient Egyptians used it in the
embalming of dead bodies. In some countries lumps
of earth are soaked with petroleum, and are employed
as fuel.
214. MINERAL TAR, or BARBADOES TAR, is a
fluid kind of bitumen, somewhat thicker than petroleum, and
nearly of the consistence of common tar. It is viscid, of a
black, brownish black, or reddish colour.
In burning its smell is disagreeable, but less pungent than
that of most other kinds of bitumen. Its weight is somewhat
greater than that of water.
In the West Indies, where this substance is principally
found, it is applied to many of the purposes for
which the preceding species is used; but its principal
// 164.png
.pn +1
repute has been obtained from its being thought useful
in disorders of the breast and lungs, though this application
of it is considered very improper. It is likewise
used as an external remedy in paralytic disorders.
215. ELASTIC BITUMEN, or MINERAL CAOUT-CHOUC,
has a strong resemblance to Indian rubber. In some
instances it is elastic, and so soft as to adhere to the fingers,
and in others brittle, and so hard as nearly to resemble asphalt
(#216:n216#).
Its colour is yellowish, reddish brown, or blackish. One
kind of this mineral, when fresh cut, nearly resembles fine
cork, both in texture and colour.
This extraordinary substance, which will expunge the
marks of black lead in the same manner as Indian rubber,
was first discovered, about the year 1786, in cavities
of the lead mine of Odin, near Castleton, in Derbyshire,
and it has not hitherto been found elsewhere.
Elastic bitumen appears to be a peculiar modification
of petroleum, in its passage to asphalt: and probably
owes its elasticity to its cellular texture, and to the
moisture with which it is combined.
216. ASPHALT, or SOLID BITUMEN, is a brittle
substance, of black or brownish black colour, and of consistence
somewhat harder than pitch.
It has nearly the same weight as water, is smooth to the
touch, does not stain the fingers, and has little or no smell unless
it be rubbed or heated. When heated, it melts, swells and
inflames; and, if pure, burns without leaving any ashes.
The ancients were well acquainted with this substance,
which is nothing more than mineral tar (#214:n214#) in
an indurated or hardened state. It is found on the
surface of volcanic productions, and floats, in solid
pieces, and in considerable abundance, on the Asphaltic
Lake, in Syria, which has thence received its name.
This lake is also called the Dead Sea, from a notion
that the odour arising from the asphalt destroys even
birds which fly over it: Maundrell, however, states that
this is not true, as he saw several birds fly about and
over it, without experiencing the slightest injury.
// 165.png
.pn +1
Asphalt is also found near ancient Babylon; and
there is reason to suppose that the mortar so celebrated
amongst the ancients, and with which the walls of Babylon
and of the Temple of Solomon were cemented, was
nothing more than a preparation of asphalt. We are
informed by Herodotus that a composition of heated
bitumen, mixed with the tops of reeds, was used by the
ancients as a cement. This account is confirmed by
modern travellers, who assert that the remains of buildings
have been discovered in which bitumen was formerly
thus employed. It is presumed to be the same
substance which, in our translation of the Old Testament,
is called pitch, and which was used by Noah, as
an exterior and interior coating of the ark; by the
mother of Moses as a coating for the little vessel in
which he was exposed; and on various other occasions.
As an article of modern utility, it is to be remarked
that the Arabians dissolve asphalt in oil, and, with the
mixture, smear their horse harness, to preserve it from
the effects of weather, and the attacks of insects. In a
state of solution it is applied, in several eastern countries,
as a covering for timber and the bottoms of ships.
It is occasionally used in the cleansing and healing of
ulcers, and other sores. In France it is manufactured
into a substance which is in considerable request for
greasing the wheels of carriages. It is used by the
makers of watch-dials, who mix it with lamp black, and
oil of turpentine; but its chief use is as an ingredient in
certain varnishes, and particularly in the varnish used
by copper-plate engravers. It is frequently adulterated
by a mixture with common pitch; but this is easily discovered
by the smell.
Besides the countries and places already mentioned,
asphalt is found in several parts of America, in the
island of Trinidad, in the province of Neufchatel, and
many parts of the Continent of Europe.
.sp 2
.h4
COAL FAMILY.
217. The component parts of coals are principally carbon or
charcoal (#48:n48#), and bitumen (#216:n216#).
// 166.png
.pn +1
.fs 85%
Some kinds of coal are laminar, and others compact. They
in general burn freely, with a bituminous odour, and leave a
considerable residuum.
.fs 100%
This invaluable mineral is found in beds, or strata,
frequently betwixt clay slate (#257:n257#) and sandstone (#267:n267#),
and seldom betwixt those of limestone (#140:n140#). It
chiefly occurs in the northern hemisphere, particularly
in countries which lie nearly in the same latitudes with
Great Britain; in Siberia, Germany, Sweden, France,
Canada, and Newfoundland; and in some of the northern
parts of China. It is stated to be abundant in New
Holland; but we have no distinct account of coal in the
continent of Africa. No fewer than seventy different
kinds of coals are brought to the London market, the
value and prices of which greatly differ. Of these the
coals called Wall’s-end, from the name of the pit, near
Newcastle, whence they are obtained, usually bear the
highest price.
218. COMMON COAL, or PIT COAL, is of black
colour, and has generally a slaty structure and foliated texture.
When handled it stains the fingers; and when burnt it cakes
more or less during combustion. Its component parts are
usually charcoal (#48:n48#) and bitumen (#216:n216#), with a small portion
of clay, and sometimes with pyrites, or sulphat of iron (#236:n236#).
What is called slaty coal contains a greater portion of clay
than other kinds.
Some foreign writers have ascribed the great wealth
possessed by this country to the coals which are here
produced in such abundance, and which facilitate, in a
very essential degree, nearly all its manufactures, and
consequently are a means of promoting its commerce
to an extent which is possessed by few other countries.
All our great manufacturing towns, Birmingham, Sheffield,
Leeds, Glasgow, &c. are situated either in the
midst of coal districts, or in places to which coals are
conveyed, with little expense, by canal carriage.
Coals are principally obtained from the neighbourhood
of Newcastle-upon-Tyne, Sunderland, and Whitehaven.
// 167.png
.pn +1
The particular places whence they are obtained
have the name of collieries, and the mines from which
they are dug are called pits. The deepest of these are
in Northumberland, and are worked at more than 900
feet below the surface of the earth. At Newcastle there
is a coal-pit near 800 feet in depth, and which, at that
depth, is wrought five miles horizontally, quite across,
and beneath the bed of the river Tyne, and under the
adjacent part of the county of Durham. At Whitehaven
the mines are of great depth, and are extended
even under the sea, to places where there is above them
sufficient depth of water for ships of great burthen,
and in which the miners are able sometimes to hear
the roaring of the water. On the contrary, in some
parts of Durham the coal lies so near the surface of the
earth that the wheels of carriages lay it open, and in
such quantity as to be sufficient for the use of the neighbourhood.
The beds of coal are of various thicknesses, from a
few inches to several feet; and in some places, it is
found advantageous to work them at a very great depth,
although their thickness does not exceed four or five
feet. The thickest bed of English coal, of any extent,
is that of the main coal in Staffordshire, which measures
about thirty feet. In many places there are several
beds above, and parallel to, each other, separated by
strata of slate, sandstone, and other minerals. Coal is
never found in chalk, and very rarely in limestone.
At Whitehaven, the principal entrance to the coalmine,
both for men and horses, is by an opening at the
bottom of a hill, through a long passage hewn in a rock.
This, by a steep descent, leads to the lowest bed of
coal. The greatest part of the descent is through
spacious galleries, which intersect other galleries;
all the coal having been cut away, except large pillars,
which, in deep parts of the mine, are three yards
high, and about twelve yards square at the base, such
great strength being there required to support the ponderous
roof. There are three distinct and parallel strata
// 168.png
.pn +1
of coal, which lie at a considerable distance above each
other, and which have a communication by pits that are
sunk between them. These strata are not always regularly
continued in the same plane. The miners occasionally
meet with veins of hard rock, which interrupt
their further progress, and, at such places, the earth, on
one side of the vein, appears to have sunk down, while
that on the opposite side has its ancient situation.
These breaks the miners call dykes (#4:n4#). When they
come to one of them, their first care is to discover whether
the coal, in the part adjoining, be higher or lower
than that in which they have been working; or, to use
their own terms, whether it be cast down or cast up.
For this purpose they examine attentively the mineral
strata on the opposite side, to see how far they correspond
with those which they have already passed
through. If the coal be cast down, they sink a pit to
it: but if it be cast up, the discovery of it is often attended
with great labour and expense.
In general the entrance to coal mines is by perpendicular
shafts, and the coals and workmen are drawn up
by machinery. As the mines frequently extend to
great distances, horizontally, beneath the surface of the
earth, peculiar care is necessary to keep them continually
ventilated with currents of fresh air, for the purpose,
not only of affording to the workmen a constant
supply of that vital fluid, but also to expel from the
mines certain noxious exhalations which are sometimes
produced in them.
One of these, denominated fire damp, is occasioned
by the generation of hydrogen gas, or inflammable air
(#45:n45#). This gas, when mixed with the common air of
the atmosphere, explodes, with great violence, on the
approach of a lighted candle, or any other flame; and
has, at different times, occasioned the loss of many valuable
lives. It is a singular circumstance, that although
it is immediately set on fire by a flame, yet it cannot be
kindled by red hot iron, nor by sparks produced
from the collision of flint and steel. Hence a machine
// 169.png
.pn +1
was, some years ago, adopted in the mines near Whitehaven
and Workington, in which a wheel formed of
steel, and in shape somewhat like that of a razor-grinder,
was turned round with very rapid motion
against a series of flints, and in such manner as to yield
to the miners sufficient light to carry on their work in
places where the flame of a candle would occasion the
most dreadful explosions. Sir Humphrey Davy has
lately invented, for the use of mines where this gas is
prevalent, what is called a safety lamp. This is a lamp
enclosed in a wire cylinder, the interstices of which are
so extremely small as, whilst it gives light, will not explode
the gas.
Another injurious exhalation in coal mines arises
from the formation of carbonic acid gas, or fixed air
(#26:n26#), and is called choke damp. It is the property of
inflammable air to rise to the upper parts; but this, on
account of its weight, occupies principally the lower
parts of mines, and occasions death by suffocation,
though it is by no means so fatal as the former. In
some mines a prevention of injury arising from each of
these gases is attained, by ascertaining the particular
crevices in the coal from which they issue, confining
them at those places within a narrow space, and, if possible,
conveying them out of the mines, through long
pipes, into the open air.
There is yet another danger attending coal mines
which requires to be provided against, and this is inundation.
Many mines have been destroyed by the flooding
of water, which springs up within them. The modes
by which this was formerly extracted were extremely
laborious, and, in numerous instances, entirely inefficacious.
By means, however, of the fire or steam engines
now in use, the quantity of water raised from mines is
perfectly astonishing. Four engines in one of the collieries
at Whitehaven discharge more than twenty hogsheads
per minute, or upwards of 30,000 hogsheads in
every twenty-four hours.
The coal trade, which at present affords so important
// 170.png
.pn +1
a nursery for our seamen, and, in numerous other respects,
yields advantages of the most beneficial description
to this country, was entirely unknown a few centuries
ago. Coals were not generally adopted as fuel
until the beginning of the reign of Charles I. They
were, however, noticed in documents anterior to the
reign of Henry III., for, that monarch, in the year
1234, renewed a charter, granted by his father, to
the inhabitants of Newcastle, by which they were permitted
to dig coal upon payment of 100l. per annum.
Coals had been introduced into London before 1306;
for in that year, the use of them as fuel was prohibited,
from the supposed tendency of their smoke to corrupt
the air. About the beginning of the sixteenth century,
the best coals were sold in London at the rate of 4s. 1d.
per chaldron, and at Newcastle for no more than 2s. 6d.
During the ensuing century, however, they were received
into such general use, that, in 1648, on a scarcity
of coal in London, many of the poor are said to
have died from want of fuel. The whole quantity of
coals imported into London has been estimated, on an
average of four years, ending in March, 1815, to amount
to 1,170,000 chaldrons per annum.
Some writers have imagined coal to be the remains
of antediluvian timber, which floated upon the waters of
the deluge until several strata of mineral substances
had been formed: others conceive it to have been antediluvian
peat bog. It is called pit coal, from the
circumstance only of its being obtained from mines or
pits; and, in London, for no better reason than its having
been conveyed thither by sea, it has the name of sea
coal.
Its uses as fuel are too extensively known to need
here any observations. By the distillation of coal an
inflammable gas is produced, which has of late been introduced
for the lighting of manufactories, and lighting
several of the streets and shops of the metropolis. This
gas is conveyed by pipes, from the reservoir in which
it is collected, to great distances; and the light which
// 171.png
.pn +1
it yields is peculiarly brilliant and beautiful. It was at
the foundery belonging to Messrs. Boulton and Watts,
at Birmingham, that the first public display of gas lights
was made, in the year 1802, on the occasion of the rejoicings
for peace. In 1805 the cotton mills of Messrs.
Phillips and Lee, at Manchester, were lighted with gas,
to the exclusion of lamps, candles, and every other
source of artificial light. In the beginning of 1816 it
was estimated that, at the three gas-light stations, in
Peter-street, Westminster, Worship-street, and Norton
Falgate, London, twenty-five chaldrons of coals were
used daily; and that these were sufficient to supply
with gas 125,000 large lamps. At the works in Dorset-street,
Fleet-street, the daily consumption of coal was
about three chaldrons, which afforded gas for 1,500
lamps.
The production of the gas light is easily effected in
miniature, by putting common coal, pounded small,
into the bowl of a tobacco-pipe, and closely covering
this with clay made into a stiff lute with water.
When the clay is dry, the bowl of the pipe must be
put into the fire, and there heated gradually. In a
few minutes a stream of gas will issue from the end of
the pipe. This may be set on fire with a piece of paper,
and will burn with a bright flame. When the gas
is no longer disengaged, there will be found in the
bowl of the pipe the remains of the coals, in the form of
coke.
It is estimated that one chaldron of good coals will
afford from 17,000, to 20,000 cubical feet of gas; and
that one of the large burners in the shops of London,
consumes about four cubical feet per hour.
Soot is produced from the smoke of burned coal, and
is used as a manure for cold, moist, and clayey meadows
and pastures: and pounded coal has been applied
to the same purpose in some parts of the Continent.
By a process called charring, coal is divested of its humid,
acid, and bituminous particles, and is converted
into a kind of cinder called coke. This is employed in
// 172.png
.pn +1
cases where intense heat is requisite, as for the smelting
of iron ore; and likewise where acid and bituminous
particles of coal would be detrimental, as in the
drying of malt.
What is usually termed culm is the refuse or dusty
coal, produced in working the common coals. It contains
much earthy matter, will not kindle in an ordinary
fire-place, but produces considerable heat and flame in
a furnace, where a strong current of air is introduced.
In England it is exempted from the high duty imposed
on other coals, and is sold at a very low price. It is
used for burning lime, making salt, and in steam
engines.
219. CANNEL COAL is of black colour, with little lustre,
is not laminar, but breaks in any direction, like pitch, and does
not stain the fingers.
This highly inflammable kind of coal is found abundantly
in the neighbourhood of Wigan, in Lancashire,
where there is an entire stratum of it about four feet in
thickness. It is also found near Whitehaven, in some
of the pits at Newcastle, and in some parts of Scotland.
Doubts have been entertained respecting the name of
this coal; but when it is recollected that in Lancashire,
whence it is chiefly brought, the word candle is usually
pronounced with the omission of the letter d, and that,
in many instances, the coal is used by the poor as a
substitute for candles, these will be immediately removed.
In Scotland it has the name of parrot coal.
No kind of coal takes fire so readily, nor burns with
so cheerful and brilliant a flame as this: and its not
soiling the fingers, like pit coal, renders the use of it
peculiarly pleasant; but it does not cake, and soon
burns away. When first kindled, it crackles and splinters
very much; and, on this account, would be dangerous,
were it not easily prevented from so doing by being
previously immersed for a little while in water. Cannel
coal has much the appearance of jet. It admits of being
turned in a lathe, and takes a good polish; and
snuff-boxes and trinkets made of it have in many instances
// 173.png
.pn +1
been sold as jet (#222:n222#). Of all the kinds of coal
that are used for gas-lights, none are said to be so useful
as this.
220. STONE COAL, KILKENNY COAL, WELSH
COAL, or GLANCE COAL, is of a dark iron-black colour,
with a metallic lustre and foliated texture; and consists almost
entirely of charcoal.
Unlike most other kinds of coal, this occurs both in
stratified masses, and in lumps, nested in clay. It is
found in several countries of the Continent, in Wales,
Scotland, and near Kilkenny in Ireland.
When laid on burning coals, it becomes red hot, emits
a blue lambent flame in the same manner as charcoal;
and is, at length, slowly consumed, leaving behind a
portion of red ashes. No smoke nor soot is produced
from this coal; but, on the contrary, it whitens the
places where the fume is condensed; and the effluvia
which it gives out are extremely suffocating.
This coal is chiefly used in the drying of malt.
221. BOVEY COAL, BROWN COAL, or BITUMINOUS
WOOD, is of brown colour, and in shape exactly
resembles the stems and branches of trees, but is usually compressed.
It is soft, somewhat flexible, and so light as nearly to
float when thrown into water.
The greatest abundance of this coal occurs at Bovey,
near Exeter, from which place it derives its name. The
lowest stratum is worked at the depth of seventy-five
feet beneath the surface of the earth. It is also found
in Scotland, Ireland, and Germany.
As fuel, the Bovey coal is used only by the poorest
classes of the community, as, notwithstanding its burning
with a clear flame, it emits a sweetish but extremely
disagreeable sulphureous gas, which is injurious to
the health of the inhabitants. It is principally used for
the burning of lime, and for the first baking of earthen
ware.
222. JET, or PITCH COAL, is a solid, black, and
opaque mineral, harder than coal, and found in detached
// 174.png
.pn +1
masses from an inch to seven or eight feet in length, having a
fine or regular structure, and a grain resembling that of
wood.
It has sometimes been confounded with cannel coal (#219:n219#), but
it is easily distinguished by its superior hardness: Jet cannot
without difficulty be scratched with a knife, whilst cannel coal
may be marked by the simple pressure of the nail.
The name of jet has been derived from Gages, a river
of Lycia, whence the ancients are said to have obtained
this substance. It is frequently cast ashore on the
eastern coasts of England, together with pieces of
amber and curious pebbles, particularly near Lowestoft
in Suffolk, and in some parts of Yorkshire, where many
persons employ their leisure in searching for it, and
forming it into various kinds of trinkets. Jet is found
in several countries of the Continent.
It is stated that in the district of Aude, in France,
there are more than 1,000 persons constantly employed
in the fabrication of jet into rosaries, buttons, ear-rings,
necklaces, bracelets, snuff-boxes, and trinkets of different
kinds. Near fifty tons weight of it are annually
used for this purpose; and articles to the value of
18,000 livres are said to be sold in Spain alone. In
Prussia the amber diggers call it black amber, because
it is found accompanying that substance; and because,
like amber, it is faintly electric, or attracts feathers and
other light objects when rubbed. They manufacture
it into various ornamental articles, and sell these to ignorant
persons, as black amber, at a great price.
In different parts of the globe the trunks of trees,
which have been long buried, have passed into the
state of jet; and, in almost all these trees may be
traced the distinctive characters of the species to which
they belong. They are more or less brittle, more or
less unctuous, according to the species, the degree of
alteration, and the nature of the soil. All of them have
a smooth and glassy fracture, but all are not adapted
for the tool of the workman. When, for instance, the
texture of the tree presents only a mass of dry fibres,
// 175.png
.pn +1
the jet obtained is dry and brittle; and cannot be used
in the forming of trinkets. But, if the texture be unctuous
the fibre acquires a considerable degree of softness,
is susceptible of being properly wrought, and receives
a perfect and beautiful polish.
A fictitious kind of jet is made of glass; and several
varieties of mineral pitch, and cannel coal, are imposed
upon ignorant purchasers for jet.
When jet is once set on fire it burns with a green
flame, and continues to burn for a considerable time,
exhaling a strong bituminous smell. If the heat be
rendered greater, it melts.
.sp 2
.h4
GRAPHITE FAMILY.
223. BLACK LEAD, or PLUMBAGO, is an inflammable
mineral, which consists of carbon, or charcoal (#48:n48#),
combined with iron, in the proportion of about nine parts of
the former to one of the latter.
It is of dark iron-grey colour, with a strong metallic lustre,
and so soft that it is easily scratched with a knife. To the
touch it is soft and greasy; and, when handled, it stains the
fingers. In weight it is about twice as heavy as water.
The name of black lead has very improperly been
given to this substance from its appearance only, as it
has no alliance whatever with lead. It is usually found
in kidney-shaped lumps of various size, and occurs in
several countries of Europe, but no where of such
excellent quality as in Borrowdale, Cumberland, where
it has the name of wadd. The vein of black lead lies
between strata of slate, and is from eight to nine feet
thick. This mine is not opened more than once every
three or four years, the quantity thus obtained being
found fully sufficient for the demand. The only other
mine of black lead in Britain is in Ayrshire, Scotland.
Artists in water-colours, if deprived of this mineral,
would find great difficulty in making their sketches; as
the marks that are erroneously made with it are more
easily expunged than those of almost any other substance.
Hundreds of thousands of pencils are every
// 176.png
.pn +1
year formed of black lead. For this purpose the mineral
is sawed into slender square pieces. These are fixed
into grooves, of the same shape, cut in cedar, or some
other soft wood; another piece of wood is then glued
upon this, and the whole is worked into a circular form.
The finer kinds of black lead are prepared for use by
being boiled in oil before they are cut. The coarser
kinds, and the refuse of the sawings, are melted with
sulphur, and then cast into coarser pencils for carpenters.
These may, in general, be easily distinguished by
their sulphureous smell. The pencils that are manufactured
in England are more esteemed on the Continent
than any others.
The powder produced in the sawing of pencils is
employed for numerous purposes. It is used for giving
a bright gloss to cast-iron grates and stoves, and defending
them from rust, and from the action of fire. It
may also be advantageously applied to the inner surface
of wooden screws, to packing presses, the axles of various
sorts of machines, to slides, and other wood work,
which are subject to friction. In this respect it is far
superior either to grease or soap. The makers of razor-strops
occasionally employ black lead in the composition
which they spread upon leather for the sharpening
of razors; and, on the Continent, it is sometimes used
for blackening the hair. A coarser kind of black lead
is used for making the vessels that are used by chemists,
called crucibles.
.sp 2
.h4
RESIN FAMILY.
224. AMBER is a substance usually of golden yellow colour,
semi-transparent, and of shining and somewhat resinous
lustre. It is occasionally seen of yellowish white colour, and
nearly opaque.
The origin of amber is unknown. From the ants
and other insects which it frequently contains, there
can be no doubt that it has once been in a fluid state:
and some writers have thought that it is a resinous juice,
gradually modified by the action of sulphuric acid
// 177.png
.pn +1
(#24:n24#); but this is entirely conjecture. The ancients
called it electron, and attributed its formation to the
sisters of Phaëton, who, lamenting the death of their
brother, were converted into poplar trees; these, it was
said, instead of tears, yielded every year this substance;
which, issuing from them in a fluid state, ran into the
river, and there became hardened.
Amber is usually found in rounded and detached
pieces, on the south coast of the Baltic, on the eastern
shores of England, and in small quantity, on those of
Sicily and the Adriatic; and a substance greatly resembling
it is occasionally found in gravel pits near
London. The only mines of amber at present known
are in Prussia. These are worked in the usual way, by
shafts and galleries, to the depth of about 100 feet.
The amber is imbedded in a stratum of fossil wood,
and occurs in rounded pieces, from a few grains to
three and even five pounds in weight. The largest
piece of amber ever known to be discovered in a detached
state was found near the surface of the ground,
in Lithuania, about twelve miles from the Baltic Sea.
It weighed more than eighteen pounds, and was
deposited in the cabinet of the King of Prussia at Berlin.
Very lately a mass of amber, weighing thirteen
pounds, was also found in Prussia. For this piece 5000
dollars are said to have been offered; but the Armenian
merchants assert that it might have been sold in Constantinople
for more than 30,000 dollars.
Anterior to the discovery or general dispersion of
precious stones from India, amber was considered of
great value as a jewel, and was employed in all kinds
of ornamental dresses. The ancient Romans were so
partial to this substance that Pliny, reprobating the
great demand for it, says, the Roman females would
give larger sums for a puppet or figure in amber, resembling
a man or woman, however small its size, than
they would for the finest man or the most valiant soldier.
Under the Emperor Nero, persons were sent
from Rome, for the purpose of collecting and purchasing
// 178.png
.pn +1
amber; and so much of it was at length obtained,
that it was used for ornamenting the nets and cordage
employed in the theatres for preventing the wild animals
from approaching the populace there assembled.
It was likewise used to ornament the armour, the biers,
and funeral apparatus of such persons as were killed.
Amber is now chiefly in request by Greek and Armenian
merchants, but it is uncertain where they dispose
of it. Some persons conjecture that it is purchased
by pilgrims previously to their journey to Mecca; and
that, on their arrival in that place, they burn it in honour
of Mahomet.
The kind most in esteem is of a bright golden yellow
colour. This is occasionally manufactured into snuff-boxes,
small vases, necklaces, bracelets, cane-heads,
and other ornamental articles, many of which are purchased
by the Turks, Russians, and Poles; but the
general demand for them has of late very much decreased.
Some years ago the German artists paid great
attention to this substance; and many experiments
were made for the purpose of discovering means of removing
its defects, and improving its beauty. It is said
that they possessed the art of liquefying it to such a
degree, that it could be run into moulds without injuring
its beauty; and that specimens of this liquefied
amber are preserved in the Electoral Cabinet at Dresden.
There are still considerable manufactories of
amber at Stolpen, Konigsberg, Dantzic, and Lubeck.
Amber, when wrought into ornaments, is first split
on a leaden plate, and then turned on a particular kind
of whetstone. The polishing of it is performed with
chalk and water, or chalk and oil; and the work is
finished by rubbing the whole with clean flannel. Without
great attention it becomes very hot, and either flies
into pieces, or takes fire during the operation.
After having been roasted or melted, amber is readily
soluble in oil, and, in this state, constitutes the basis
of several kinds of varnish. It was formerly much used
in medicine, but, in this respect, it is now almost wholly
// 179.png
.pn +1
neglected. Some persons, however, have still an absurd
notion that a collar or necklace of amber, tied
round an infant’s neck, will enable it to cut its teeth in
safety. Oil of amber combined with liquid ammonia
constitutes a white soapy liquor called eau-de-luce.
It has already been mentioned that insects are occasionally
found in amber. These are generally in a very
perfect state, and consist of flies, small moths, &c.
Grains of sand, pieces of iron pyrites, and the leaves
of plants, are also sometimes found in it. Insects, sand,
and other substances, are likewise remarked in a species
of gum, called gum animè, which, in colour, appearance,
and qualities, so nearly resembles amber, that it
is almost impossible to distinguish the two substances
from each other. Large productions, which were formerly
supposed to have been made of amber, such as
a column ten feet high in the Florentine Museum, are
now usually considered to have been formed of this
gum; and many of the large beads of what are sold as
amber necklaces are made of it.
If a piece of amber be fixed on the point of a knife
and lighted, it will burn entirely away, emitting at the
same time a white smoke, and a somewhat agreeable
though sickly odour. When rubbed it has the property
of attracting light bodies; hence one of the ancient
Greek philosophers attributed to it a certain kind of
life. From the name of electron, which was given to
it by them, in consequence of this property, we derive
our word electricity.
// 180.png
.pn +1
.sp 2
.pb
.sp 4
.h3
CLASS IV.–METALLIC SUBSTANCES.
.hr 10%
.h4
OF METALS IN GENERAL.
.sp 2
225. METALS, in a perfect state, are easily
distinguished from other minerals, by a peculiar brilliancy which
pervades their whole substance, and which has the name of metallic
lustre; by their complete opacity, and their great weight in
proportion to that of other mineral substances.
When taken from the earth they are found in one or other
of the four following states: 1. In a native or metallic state,
2. Combined with sulphur, 3. In a state of oxide (#21:n21#)
4. Combined with acid.
Metals, when found in a state of combination with
other substances, have the name of ores. They are in
general deposited in veins (#4:n4#), of various thickness,
and at various depths in the earth. The mode of obtaining
them is to penetrate from the surface of the
earth to the vein, and there to follow it, in whatever
direction it may lie. The hollow places thus formed
are called mines, and the men employed in them are
denominated miners. When the veins are at a great
depth, or extend to any considerable distance beneath
the surface of the earth, it is necessary, at intervals, to
make openings, or shafts, to the surface, for the admission
and circulation of the air; and also to draw off
the water which collects at the bottom, by drains,
pumps, or steam-engines, as the situation or circumstances
require.
After the metallic ores are drawn from the mine,
they, in general, go through several processes before
they are in a state fit for use. Some of them are first
washed in running water, to clear them from earthy
// 181.png
.pn +1
particles. They are then piled with combustible substances,
and burnt or roasted, for the purpose of ridding
them of the sulphur or arsenic with which they
may happen to be combined, and which rises from them
in a state of fume or smoke. Thus, having been freed
from impurities, they undergo the operation of melting,
in furnaces constructed according to the nature of the
respective metals, or the uses to which they are to be
subsequently applied.
The knowledge of metals is a subject of great importance
to mankind. Their use in trade is so frequent,
and in the arts so various and so interesting, that few
objects can be more worthy of attention than these.
.sp 2
.pb
.sp 4
.h4
ORDER I.—MALLEABLE METALS;
.sp 2
.fs 85%
OR, SUCH AS ARE CAPABLE OF BEING FLATTENED OR
ELONGATED BY THE HAMMER, WITHOUT TEARING
OR BREAKING.
.fs 100%
.hr 10%
226. PLATINA, the most ponderous of all the metals
with which we are acquainted, is, when purified, about twenty
times heavier than water. It is also one of the hardest and
most difficult to be melted, is of white colour, but darker and
not so bright as silver, and is found only in small blunted and
angular grains or scales in the sands of some of the rivers in
South America.
If platina could be obtained in sufficient quantity, it
would perhaps be the most valuable of all metals. The
important uses to which it is applicable may easily be
imagined when we state that it is nearly as hard as
iron, and that the most intense fire and most powerful
acids have scarcely any effect upon it. Platina is not
fusible by the heat of a forge, but requires either the
concentrated rays of the sun in a burning mirror, the
// 182.png
.pn +1
galvanic electricity, or a flame produced by the agency
of oxygen gas.
It is admirably adapted for the uses of the philosophical
chemist: although vessels made of it must always
be found expensive, from its being necessary to
solder them with gold; and although it has the disadvantage
of being subject to corrosion by the application
or use of caustic alkalies. Vessels made of it are not
liable to be broken, and are as indestructible as those
made of gold. When properly refined, its colour is
somewhat betwixt that of silver and iron. Not being
liable to tarnish like silver, platina is manufactured into
several kinds of trinkets.
Its ductility is so great that it may be rolled into
plates, or drawn into wire; and platina wire, for strength
and tenacity, is considered much preferable to that
either of gold or silver of equal thickness. Platina is
also made into mirrors for reflecting telescopes, into
mathematical instruments, pendulums, and clock-work;
particularly where it is requisite that the construction
of these should be more than usually correct,
as platina is not only free from liability to rust, but is
likewise subject to very little dilatation by heat. It is
sometimes beaten into leaves and applied to porcelain,
in the same manner as leaf gold; and its oxide (#21:n21#) is
used in enamel painting, and might be used, with great
advantage, in the painting and ornamenting of porcelain.
The platina employed for all these purposes is repeatedly
melted with arsenic, as without the aid of this it could
only be obtained in very small masses, owing to the intense
heat that is required for its fusion.
This extraordinary metal was unknown in Europe
until about the year 1735, when it was first brought
from South America by Don Antonio Ulloa.
227. GOLD is a metal distinguished by its yellow colour;
by its being next in weight to platina, softer than silver, but
considerably more hard than tin; and being more easily melted
than copper.
It is found in various states, massive, in grains, small
// 183.png
.pn +1
scales, and capillary, or in small branches. It cannot be dissolved
in any acid except that called aqua regia (#207:n207#), and is
more than nineteen times heavier than water.
The countries of hot climates are those chiefly in
which gold is discovered. It abounds in the sands of
many African rivers, and is very common in several
districts both of South America and India. The gold
mines of Lima and Peru have had great celebrity; but,
since the late commotions in the Spanish colonies, the
working of them has been much neglected. It is from
Brazil that the greatest part of the gold which is seen
in commerce is brought. The annual produce of the
various gold mines in America has been estimated at
nearly 9,500,000l. sterling.
The principal gold mines in Europe are those of
Hungary, and next to them those of Saltzburg. Spain
is probably very rich in gold. Considerable mines were
worked there in former times, particularly in the province
of Asturia; but, after the discovery of America,
these were given up or lost. Gold has been found in
Sweden and Norway, and also in several parts of Ireland,
but particularly in the county of Wicklow.—Among
the sands of a mountain stream in that county,
and among the sand of the valley on each side, lumps
of gold are occasionally found. Pieces have been discovered
which weighed twenty-two ounces, but they
are generally much smaller, from two or three ounces
to a few grains. It is said that lumps of gold, of large
size, have been used as weights in some of the common
shops, and that others have been placed to keep open
the doors of cottages and houses in some parts of Ireland,
the owners not knowing what they were. Gold
is also occasionally found in Cornwall, and some other
counties of England. Wherever it occurs it is commonly
observed in a state of alloy with copper or silver,
and in the form of grains, plates, or small crystals.
Gold was formerly obtained in Scotland. It is asserted
that, at the marriage of James V. there were covered
dishes filled with coins made of Scottish gold,
// 184.png
.pn +1
and that a portion of these was presented to each of the
guests by way of dessert. Very extensive operations
for the discovery of gold were carried on during the
reign of Queen Elizabeth, at Leadhills, in Lanarkshire,
under the direction of an Englishman whose name was
Bulmer. The trenches, the heaps of soil that were turned
up, and other marks of these operations, are yet visible
near the road between Leadhills and Elvanfoot. It is
said that 300 men were then employed; and that, in
the course of a few years, a quantity of gold was collected,
equal in value to 100,000l. sterling. Not many
years ago similar operations were commenced under
the superintendence of a celebrated manager of the
Scottish lead mines. The gold was found immediately
under the vegetable soil; and the method of obtaining
it was to direct a small stream of water, so as to carry
the soil along with it, to basins or hollow places, where
the water might deposit the matters carried down by
the force of its current. The matter thus deposited was
repeatedly washed, till the whole of the earthy substances
were carried off. The gold, being heaviest,
sunk to the bottom, and remained behind. The soil
still furnishes gold; but the produce would by no means
be equal to the expense of collecting it. Searching for
gold, therefore, is now regarded only as an amusement,
and not as a source of profit. Grains of this metal
are sometimes found, after great floods, among the
sand of brooks in different parts of Scotland.
The mode of extracting gold from its ore is by reducing
it into a fine powder, and mixing this powder
with quicksilver (#228:n228#). The latter having the quality
of uniting with itself every particle of the precious
metal, but being incapable of union with the other substances,
extracts it even from the largest portions of
earth. The quicksilver, which has absorbed the gold,
is then separated by means of heat; it flies off in vapour,
and leaves the other metal in the vessel used for the
operation.
// 185.png
.pn +1
Gold has been known, and in request, from the very
earliest ages of the world. By the assent of civilized
nations, it has become the representative of wealth
under the form of money; and it is now an universal circulating
medium for the purchase of all kinds of commodities.
It has been chosen to occupy this important
place on account of its scarcity, its weight, and other
valuable properties.
As gold is not liable to tarnish or rust, it is frequently
employed for ornaments of dress. But, beyond its use
in the coinage, its most important uses are for goldsmith’s
work, in jewellery, and for gilding. In each of
these its standard or purity is different. That denominated
coinage, or sterling gold, consists of an alloy of
about twenty-two parts of gold with two parts of
copper; whilst gold of the new standard, of which gold
plate, watch-cases, and many other articles are made,
consists of only eighteen parts of gold, and six parts of
copper. Each of these is stamped at Goldsmiths’ Hall;
the former with a lion, a leopard’s head (the mark of the
goldsmith’s company), a letter denoting the year, the
king’s head, and the manufacturer’s initials; the latter
is stamped with the king’s head, letter for the year, a
crown, the number 18 to designate its quality, and the
manufacturers initials. The coinage gold of Portugal
and America is of the same standard as our own; that
of France is somewhat inferior; and Spanish gold is
inferior to the French. The Dutch ducats and some
of the Moorish coins are of gold unalloyed. Trinket
gold, which is unstamped, is in general much less pure
than any of the above; and the pale gold which is used
by jewellers is an alloy of gold with silver.
The ductility and tenacity of this metal, particularly
when alloyed with copper, are extremely remarkable,
and are fully proved by the great extent to which a
very small quantity of it may be beaten into leaves, or
drawn into wire. Leaves of gold may be beaten so
thin, that a single grain may be made into fifty-six
// 186.png
.pn +1
leaves, each an inch square. These leaves are only
1/282000 of an inch thick; and the gold leaf which is
used to cover silver wire is but the twelfth part of that
thickness. An ounce of gold upon silver wire is capable
of being extended more than 1,300 miles in
length: and sixteen ounces of gold, which, in the form
of a cube, would not measure more than an inch and a
quarter on each side, will completely gild a silver wire
in length sufficient to compass the whole earth like a
hoop.
Gold is beaten into leaves upon a smooth block of
marble, fitted into the middle of a wooden frame about
two feet square, in such manner that the surfaces of
the marble and of the frame are exactly level. On three
of the sides there is a high ledge; and the front, which
is open, has a flap of leather attached to it, which the
man who beats the gold uses as an apron for preserving
the fragments that fall off. In this process there are
three kinds of animal membranes used, some of which
are laid between the leaves to prevent their uniting
together, and others over them to defend them from
being injured by the hammer. The exterior cover is
of parchment. For interlaying with the gold, the
smoothest and closest vellum that can be procured is
first used; and, when the gold becomes thinner, this is
exchanged for much finer skin, made of the entrails of
oxen, prepared for this express purpose, and hence
called gold beater’s skin. After the leaf has been beaten
to a sufficient degree of thinness, it is taken up by a
cane instrument, and thrown flat upon a leathern
cushion, where it is cut to a proper size with a square
frame of cane, or wood edged with cane. These pieces
are then fitted into books of twenty-five leaves each,
the paper of which has been well smoothed, and rubbed
with red bole (#127:n127#), to prevent them from sticking.
The leaves are about three inches square, and the gold
of each book weighs somewhat more than four grains
and a half.
// 187.png
.pn +1
It was anciently the custom to beat gold into thin
plates, and to gild the walls of apartments, the surfaces
of dishes, drinking utensils, and other articles, by covering
them with such. But this was not only an expensive,
but it must have been a most clumsy mode of
ornament. The present modes of gilding are very different.
When wood is to be gilded, the surface is first
smeared with an adhesive kind of oil, or with a kind
of glue called size; and the gold leaf, above mentioned,
is then spread upon it by a tuft of cotton or other
soft substance.
The gilding of iron or copper is performed by cleaning
and polishing its surface, and then heating it till it
has a blue colour. When this has been done, a layer of
gold leaf is put on, slightly burnished down, and exposed
to a gentle fire. It is usual, in common work, to
place three such layers, or four at the most, each consisting
of a single leaf. The heating is repeated at each
layer, and last of all the work is burnished. For gilding
in or moulu, as it is denominated by the French, an
amalgam consisting of ten parts of mercury and one
part of gold is used. This is spread upon the metal,
and is afterwards exposed to the action of a fire sufficiently
strong to evaporate the mercury and leave the
gold behind. The gilding in or moulu is much more
solid and permanent than that by the former method.
When gilding is pale and dirty, it may be revived by
means of what is called gilding wax, a composition of
yellow wax, bole (#127:n127#), verdigris (#230:n230#), and alum.
A very beautiful gilding upon metals, and particularly
upon silver, is effected by soaking clean linen rags in a
solution of gold made by aqua regia (#207:n207#). The rags are
dried and burnt; and the ashes are carefully preserved.
These ashes are used by taking a sound cork, moistening
it with a little water, dipping it into the ashes, and
then rubbing strongly a portion of them on the surface
of the silver, which should be perfectly clean and bright.
By this simple and economical process, it will be covered
// 188.png
.pn +1
with an extremely thin coating of gold, the colour
and brilliancy of which may be heightened by burnishing.
The ornaments upon snuff-boxes, fans, and various
kinds of trinkets, are merely thin plates of silver, gilded
in this manner.
The edges of tea-cups, and other similar articles, may
be gilded, though not in a very durable manner, by
applying a thin coat of amber varnish (#224:n224#), and then
placing leaf-gold upon it. When the varnish is dry, the
gold is to be burnished.
Gold, in a state of solution, is sometimes used for
staining marble, ivory, ornamental feathers, and other
articles, a purple-red colour, which cannot be effaced.
By chemical processes an oxide (#21:n21#) is obtained from
this metal, which is employed for giving those beautiful
shades of lilac, rose colour, red and purple, which we
observe in glass and porcelain.
A gold powder for painting may be made by uniting
one part of gold with eight parts of mercury (#228:n228#), and
afterwards evaporating the latter by heat.
The article denominated gold wire is generally silver
wire gilded, very little wire being made entirely of gold.
Its uses are chiefly for embroidery and filagree work.
Gold thread consists of flatted silver gilt wire, laid over
a thread of yellow silk, by twisting it in a machine with
iron bobbins. It is of this, and not of gold, that the
article called gold lace is made. The Chinese, instead
of flatted wire, use slips of gilt paper, which they interweave
in their stuffs, and twist upon silk threads.
228. MERCURY, in its native state, is called quicksilver,
and is found in small globules of shining, silvery appearance,
scattered through different kinds of stones, clay, and ores. It is
nearly fourteen times heavier than water.
The principal ore of mercury, and that from which the
metal is chiefly obtained, is cinnabar. This is of red colour,
and consists of mercury mineralized with sulphur. It is
sometimes found in a massive state, sometimes in grains, and
sometimes crystallized; and chiefly among rocks of the coal
formation.
// 189.png
.pn +1
The most productive mines of cinnabar are in the
palatinate of Germany, at Idria in Carniola, and at Almaden
in Spain. Those of Idria are supposed to be
more valuable than any of the others. Their first discovery,
which was somewhat more than three hundred
years ago, was made in a very extraordinary manner.
This part of the country was then much inhabited by
coopers; and one of the men, on retiring from work in
the evening, placed a new tub under a dropping spring,
to try if it would hold water; and, when he came in the
morning, he found it so heavy that he could scarcely
move it. Examining into the cause of this extraordinary
circumstance, the man observed that it was owing
to a shining and ponderous fluid which was at the bottom.
The affair was noised abroad, and a society of
persons was formed to search further, and discover the
mine from which this quicksilver had flowed. Such
was their success that the reigning Duke of Austria paid
them a compensation for the discovery, and took the
mine into his own possession. The greatest perpendicular
depth of this mine is now more than 830 feet. It
is descended by buckets, or by ladders placed obliquely
in a zigzag direction. In some parts of the mine the
pure metal flows in small streams, so that in six hours a
man has been known to collect more than thirty-six
pounds weight of it. In other parts it is found in a
multitude of little drops, either in ores or in clay. The
whole produce of the mine is said to exceed a hundred
tons weight of mercury per annum.
It has been asserted that, several years ago, in digging
out clay for the foundation of a house opposite to
the King’s Arms inn, in the street called Hyde-hill, in
Berwick-upon-Tweed, a quantity of native mercury was
discovered. The clay, when dug out, lay for some time
in the place to which it was conveyed; and the mercury
was observed to exude from the small fissures or cracks
that were formed as it dried. It is said that, several
years afterwards, in making some alteration in the yard
of the same house, the workmen penetrated into the
// 190.png
.pn +1
same bed of clay; and that it then appeared to be
impregnated with native mercury, which ran out in
small globules.
Mercury is sometimes imported into Europe from
Peru, and from the East Indies.
The mode of extracting it from cinnabar is said to be
by mixing this ore either with pounded chalk, or with
half its weight of iron filings, and distilling it in a stoneware
retort. By this process the sulphur combines with
the iron, and the mercury, in a state of purity, passes
into the receiver.
When pure or native mercury occurs in mixture with
other substances, these are stamped or ground into a
coarse powder. Water is poured upon them; they
are briskly stirred until the water becomes thick and
turbid, and then are left to settle. This operation is
repeated till the water runs off perfectly clear. The
substance at the bottom, which is principally mercury,
is then put into large iron retorts and the metal is
obtained, free from all extraneous matters, by distillation.
It is the singular property of this metal, which has
no other alliance whatever with silver than its appearance,
to be capable of division, by the least effort, into
an indefinite number of particles, each of which assumes
a spherical form; and to be always in a fluid state in
the common temperature of our atmosphere. Even
during the most intense frost, it still retains its fluidity.
By the effect, however, of extreme cold artificially
produced, mercury becomes a solid metal, and in this
state may be beaten with a hammer and extended
without breaking; but care must be taken that it does
not touch the fingers, as it would blister them and
cause unpleasant sores, in the same manner as any
burning substance.
Mercury has been known from the remotest ages;
and it was employed by the ancients in gilding, and in
the operations of separating gold and silver from their
// 191.png
.pn +1
ores, in the same manner as at present. Being the
heaviest of all fluids of which we have any knowledge,
and not congealing in the temperature of our climate,
it has been preferred, before all others, for barometers,
as a measure of the weight of the atmosphere. And, as
heat dilates mercury similarly to other fluids, it is likewise
made into thermometers. Mercury is sometimes
used in medicine in its pure metallic state.
The combinations of mercury with other metals are
termed amalgams. That of mercury and gold is formed
so readily, that if gold be dipped into mercury, its surface
immediately becomes as white as silver. An
amalgam of mercury and gold is employed for the gilding,
and of mercury and silver for the silvering of metals.
Mercury and tin combined together form the substance
that is used for the silvering of looking-glasses.
The process is as follows: A quantity of tin-foil, equal
in size to the glass, is evenly placed on a flat stone or
table; and mercury, in which some tin has been dissolved,
is poured upon it, and spread with a feather, or
bunch of cloth, until its union has covered every part.
A plate of glass is then cautiously slided upon it, from
one end to the other, in such manner that part of the
redundant mercury is driven off, or swept away before
its edge. The remainder is now united to the tin. The
glass is then loaded with weights all over, so as to press
out still more of the mercury. By inclining the table,
this remaining mercury becomes discharged; and, in a
few hours, the rest of the tin-foil and mercury adhere
so firmly to the glass, that the weight may be removed
without any danger of its falling. About two ounces
of mercury are requisite for covering, in this manner,
three square feet of glass.
By means of mercury a fulminating powder is made,
which, when struck with a hammer on an anvil or flat
iron, such as is used by laundresses, explodes with a
stunning and disagreeable report, and with such force
// 192.png
.pn +1
as to indent both the anvil and the hammer. Four or
five grains are as much of this powder as ought to be
used for such experiments. Its force is much greater
than that of gunpowder, but does not extend so far.
Hence it is a substance which might be rendered of
great use in the blasting of rocks.
Corrosive sublimate is an extremely poisonous preparation
from mercury. Among other uses, it is employed
by dyers as a mordant to fix their colours. From certain
proportions of corrosive sublimate rubbed together,
until they are perfectly incorporated, is formed calomel;
a salt which, of late years, has been extensively
and most usefully employed in medicine.
A valuable red colour or pigment called vermilion,
or artificial cinnabar, which was as well known to the
ancients as it is to the moderns, is usually formed of
three parts of mercury and one of sulphur, melted together,
heated to redness, and then sublimated out of
contact of the air. The manufacture of vermilion was
long kept a secret by the Dutch; and it is stated that,
before the late war, nearly 50,000 pounds weight of it
were annually made, in three furnaces, by four workmen,
near Amsterdam. Native cinnabar is sometimes
used for the same purpose; but the artificial kind is
preferred on account of the purity and brightness of its
colour.
229. SILVER is a white, brilliant, sonorous, and ductile
metal, somewhat more than ten times heavier than water.
It is found in different states. Of these the principal is
denominated native silver, from its being nearly in a state of
purity. Native silver sometimes occurs in small lumps, sometimes
in a crystallized form, and sometimes in leaves, threads, or
wire. In many instances the latter are so connected with each
other as to resemble the branches of trees, in which case the ore
is called dendritic. There are also several ores of silver, in
which this metal is combined with lead, antimony, arsenic,
sulphur, and other substances.
The silver that is produced from the mines of Potosi,
in South America, is of the dendritic kind; and is considered
// 193.png
.pn +1
by the Spaniards as the purest that is known.
A range of mountains near Potosi, about twenty miles
in circumference, is said to be perforated by more than
300 shafts, or openings of mines, and to produce, in the
whole, from 30,000 to 40,000 dollars’ worth of ore per
week. The annual produce of the silver mines in
America has been estimated at near 2,400,000l. sterling.
Silver is also found in several parts of Europe; and,
some years ago, there were mines of this metal, worked
to a great extent, at Konigsberg in Norway. These
were discovered in 1623, and they were found so profitable,
that in 1751 forty-one shafts and twelve veins
were wrought there; and 3,500 officers, artificers, and
labourers, were employed. The perpendicular depth
of the principal shaft was more than 750 feet. Specimens
of native silver are not uncommon from some of
the copper-mines of Cornwall; and, many years ago, a
vein of silver ore was, for a short time, wrought with
considerable advantage in the parish of Alva, Stirlingshire,
Scotland. It is said that from 40,000l. to
50,000l. worth of silver was obtained from it before the
repository was exhausted. We are informed that a
mass of capillary native silver was found, in veins traversing
the blue-coloured limestone of Isla, one of the
Western Islands of Scotland. Great quantities of silver
are extracted from lead. There was lately melted in
one refining house in London 50,000l. worth of this
metal, from lead of the Beralston mines in Devonshire.
Different methods are employed, in different countries,
to extract silver from its ore. In Mexico and
Peru the mineral is pounded, roasted, washed, and
then mixed with mercury in vessels filled with water;
a mill being employed for the more perfectly agitating
and mingling them. By this process the silver combines
with the mercury. The alloy thus obtained,
after undergoing some further processes, is submitted
to the action of heat, by which the mercury passes off
in a state of vapour, leaving the silver behind. The
silver is then melted and cast into bars or ingots. In
// 194.png
.pn +1
other countries, after the earthy matters are cleared
from the silver ore by pounding and washing, the remainder
is melted with lead: which, by a subsequent
process, is separated, and leaves the silver alone and
pure.
This metal ranks next in value to gold. Like gold,
it is coined into money, and is manufactured into various
kinds of utensils, such as goblets, vases, spoons,
and dishes, which have the general appellation of silver
plate. For all these purposes it is alloyed with copper,
which does not affect its whiteness, and is not easily
detected, unless it be in too great proportion: the intention
of this is to render it harder than it would
otherwise be, and thereby the better to adapt it to receive
fine and sharp impressions on being cast. Our
standard silver is composed of somewhat more than 12¼
parts of pure metal and one part of copper; and the
metal of this standard is used, both for silver plate, and
in the coinage. The mark or stamp which is given to
it at Goldsmiths’ Hall is similar to that which has been
explained for sterling gold.
After platina (#226:n226#) and gold (#227:n227#), silver is considered
the most unchangeable of all metals. The air does not
easily act upon its surface in such manner as to injure
it; but, when long exposed to the atmosphere, especially
in frequented or smoky places, it acquires a covering or
rust of dark brown colour, which, on examination, is
found to be what chemists denominate sulphuret of silver.
The fumes of sulphur and other inflammable substances
blacken silver. Various powders have been contrived
with a view to restore to plate its original lustre; but
these should be used with caution, as some of them are
very injurious.
Silver is nearly as ductile as gold. It may be beaten
into leaves so thin that a single grain in weight will
cover a space of more than fifty-one inches; and it may
be drawn into wire much finer than a human hair, indeed
so fine that a single grain of silver has, in this
// 195.png
.pn +1
form, been extended nearly to the length of 400 feet.
It is this wire gilded that has the name of gold wire;
and what is denominated gold lace (#227:n227#) is but flatted
silver thread gilt, twisted round silk, and woven.
The plating of copper with silver is a very useful
operation, and is thus performed. Plates of silver are
bound with iron wire, upon small ingots of copper.
The quantity generally allowed is one ounce of silver
to twelve ounces of copper. The surface of the plate
of silver is made not quite so large as that of the copper;
and upon the edges of the copper, which are not
covered by the silver, a little borax (#204:n204#) is put. By
exposing the whole to a strong heat, the borax melts;
and, in melting, contributes to fuse that part of the silver
to which it is contiguous, and to attach it, in that state,
to the copper. The ingot, with its silver plate, is then
rolled between steel rollers moved by machinery, till it
is of proper thickness. It is afterwards cut into such
sizes and to such shapes as may be required for use.
An ounce of silver is thus often rolled out into a surface
of three square feet, having its thickness, upon the copper,
not more than the three-thousandth part of an
inch. Hence we ought not to be surprised at the silver
being soon worn from the sharp edges of plated goods.
To prevent this, it is customary, with the best articles,
to have all the edges, and the parts liable to be worn,
formed, to a considerable thickness, of silver.
What is called French plate is made by heating copper,
or more frequently, brass, to a certain degree, then
applying leaf-silver to the surface, and strongly rubbing
it with a burnisher. The durability of this plating depends
of course on the number of leaves which are applied
on a given surface. For ornaments that are not
much used ten leaves may be sufficient; but a hundred
will not last long, if the metal be exposed to frequent
handling or washing.
Besides the above, there are various modes of silvering
metal articles, or, as it is called, washing them with
// 196.png
.pn +1
silver. All these are performed by different chemical
preparations of this metal.
The article denominated shell-silver, used by painters,
is prepared, by carefully grinding silver-leaf, with a
little honey or gum water upon a slab, or in a mortar,
and separating the honey or gum by means of water.
When this is washed away, the silver may be put on
paper, or kept in shells, for use. When it is to be used,
it must again be diluted with gum water.
The application of silver-leaf for the silvering of paper
or wood is similar to that of gold-leaf (#227:n227#).
Silver, dissolved in aqua fortis (nitric acid, 30), yields
crystals, which, afterwards melted in crucibles, form
that grey mass usually called lunar caustic, and by chemists
nitrat of silver. This preparation is of considerable
use in surgical cases, being employed to keep down
fungous or proud flesh, in wounds and ulcers, and also
for the consuming of warts, small wens, and other excrescences
upon the skin. It is likewise, though a most
violent medicine, sometimes given internally, but in
very small doses, to persons subject to epileptic fits.
The liquid in which the silver is dissolved becomes excessively
caustic. It gives to the skin, the hair, and
almost all animal substances, an indelible black colour.
Hence it is often used as a specific for dyeing the human
hair. No person, however, would employ it for
this purpose, who was acquainted with its injurious
qualities, not only to the hair itself, but also to the skin,
if permitted to come in contact with it.
The article called indelible, or permanent marking ink,
for marking linen, and other wearing apparel, is formed
by dissolving, in a glass mortar, two drachms of nitrat
of silver, in six drachms of pure water, and then adding
to them two drachms, by measure, of thick gum water.
This is the ink for writing on the linen.—In another
vessel dissolve half an ounce of salt of tartar, or of the
subcarbonat of soda, of commerce, in four ounces of
water; and add to the solution half an ounce, by measure,
of thick gum water. This forms the preparatory
// 197.png
.pn +1
liquor. With this the linen is to be thoroughly wetted
at the part intended to be marked. The linen is to be
dried, and then to be written upon by a clean pen dipped
in the marking ink. The letters will at first be
pale, but by exposure to light and heat, they will soon
become black; and be so permanently fixed, that no
washing nor bleaching can efface them.
The attention of the curious has of late been turned
to a very extraordinary compound called fulminating
silver, which explodes without heat, and with even the
slightest degree of friction. Of this compound little
fulminating balls have been made. These are globules
of thin glass, each somewhat larger than a pea, and
containing a grain or two of fulminating silver. After
the silver is put in, it is secured by a piece of soft paper,
pasted over the ball, so as completely to cover it.
These balls explode by merely crushing them under the
heel of the shoe. What are called fulminating bombs
are similar balls, but of the size of hazel nuts. No one
should attempt to explode these by crushing them with
the shoe, as their explosive effect is so violent as sometimes
to prove injurious.
Fulminating silver requires the utmost care. It
should never be put into phials, nor should it be in any
way handled so as to produce much friction. It is the
most dangerous preparation that is known. The mere
touch of a hard substance will sometimes explode it;
and its very preparation is so hazardous that this ought
never to be attempted without a mask upon the face
with strong glass eyes.
The following are three pleasing experiments with
preparations of silver:
1. Mix or amalgamate together four parts of silver
leaf with two parts of mercury (#228:n228#) and dissolve this
in diluted aqua fortis. To the solution add as much
water as will be equal to thirty times the weight of the
metals employed. Pour a portion of the above mixture
into a phial, and place at the bottom a small piece of
silver. After it has stood awhile, little filaments of silver
// 198.png
.pn +1
will be seen to shoot up from it somewhat in the form
of a shrub. This apparent vegetation is popularly called
the tree of Diana.
2. A production nearly similar may be obtained by
adding a little quicksilver to a solution of nitrat of silver
in water.
3. Drop upon a clean plate of copper a small quantity
of solution of lunar caustic, or nitrat of silver. In
a short time a metallic vegetation will be perceptible,
branching out in pleasing forms, and in various directions.
230. COPPER is a red or orange-coloured metal, about
nine times heavier than water. It is the most sonorous of all
metals, and, except iron, the most elastic.
It is found under a great variety of forms, sometimes in
masses of pure metal, but, more frequently, in combination with
other substances, particularly sulphur.
There are valuable copper mines in every quarter of
the world; and the use of copper is probably of greater
antiquity than that of any other metal. It is mentioned
in the Old Testament; and, at a very early period, domestic
utensils and instruments of war were made of
bronze, or a compound of copper and tin. Even during
the Trojan war, as we learn from Homer, the combatants
had no other armour than what was made of bronze.
The Greek and Roman sculptors are said to have executed
fine works of art in porphyry, granite, and other
hard minerals, by means of copper instruments; whence
historians have been induced to believe that the ancients
possessed the secret of rendering this metal as hard as
steel: some of them even imagined that they had the
means of converting it into steel.
Copper is very abundant in several parts of Great
Britain, particularly in the island of Anglesea. The
copper mines of Anglesea are situated on the top of a
mountain, and form an enormous cavity more than five
hundred yards long, a hundred yards broad, and a
hundred yards deep. The ore is got from the mine by
pickaxes, and blasting with gunpowder. It is then
// 199.png
.pn +1
broken with hammers into small pieces, an operation
which is chiefly performed by women and children.
After this, it is piled into kilns of great length, and
each about six feet high; from the upper parts of
which flues are attached that communicate with what
are called sulphur chambers. The kilns are closely
covered; and fires are lighted in different parts, that
the ore may undergo the process of roasting. The
whole mass gradually kindles, and the sulphur, which is
combined with the ore, is expelled in fumes, by the
heat, and is conveyed, through the flues, to the sulphur
chamber. This process occupies from three to ten
months, according to the size of the kilns; and, during
that period, the sulphur chamber is cleared four or five
times. When the operation is complete, or the ore is
freed from the sulphur, it is taken to places denominated
slacking pits. It is subsequently conveyed to
the smelting houses, where, by intense heat, the pure
metal is drawn off in a fluid state.
As the water, which passes through several parts of
the Paris mine, is strongly impregnated with sulphat of
copper (#209:n209#), or copper held in solution by sulphuric
acid (#24:n24#), the proprietors turn the course of this water
through certain large and shallow pits, which they have
formed for the purpose, and in each of which they
place a quantity of iron. A decomposition here takes
place: the iron is corroded, and, at length, entirely
dissolved, and the copper, in the form of a brown mud,
falls to the bottom. One ton weight of iron, thus immersed,
will produce nearly two tons of copper mud,
each of which, when melted, will yield sixteen hundred
weight of metal. This mode of obtaining copper is said
to have been an accidental discovery from one of the
workmen, several years ago, having left a shovel in the
water, which, when afterwards taken out, appeared
changed into copper.
The magnitude of the above mentioned copper works
may readily be conceived, when it is stated that the beds
of ore are, in some places, more than sixty feet in depth:
// 200.png
.pn +1
that the proprietors employ more than 1000 workmen;
and that they ship, from the adjacent port of Amlwch,
upwards of 20,000 tons of copper, annually.
There is at Ecton, in Staffordshire, a copper mine
which is now worked at the depth of 1416 feet below
the surface of the ground. This is the deepest mine in
England.
The uses of copper are numerous and important.
When rolled into sheets, betwixt large iron cylinders, it
is employed for the covering of houses, sheathing the bottoms
of ships, and other purposes. As a covering for
houses, copper is lighter than slate, but whether it be
more durable has not been yet ascertained. The coppering
of ships tends to facilitate their progress through
the water, by presenting a smoother surface than that of
wood, and not permitting shell animals to fasten to it as
they do to wood. It likewise preserves the bottoms of
the ships from being punctured by marine worms; and
consequently secures to them a longer duration than they
would otherwise have. Plates, or flat pieces of copper,
are used by artists for engraving pictures upon, either
by cutting them with a sharp steel instrument, or corroding
them with aqua fortis (#206:n206#), in lines drawn by a
needle through a thin coat of wax spread upon their
surface.
Copper is manufactured into various kinds of cooking
utensils. Great care, however, ought to be taken
that acid liquors, or even water intended for drinking,
or to be mixed with food, be not suffered to stand long
in such vessels, otherwise they will dissolve so much of
the metal as to give them disagreeable and even poisonous
qualities. Yet, it is remarkable that, while acid
liquors are kept boiling, they do not seem to dissolve
any of the metal. Hence it is that confectioners, by
skilful management, prepare the most acid syrups in
copper vessels, without their receiving any unpleasant
taste or injurious quality from the metal. All vessels
formed of this metal which are employed in cookery,
// 201.png
.pn +1
ought to have their inner surface covered with a coat of
tin (#238:n238#).
As copper does not, like iron, strike fire by collision,
it has on this, as well as on some other accounts, been
substituted for iron in the machinery which is employed
in gunpowder mills. It is also made into water pipes,
and sometimes into sash frames. Under the hammer it
is capable of being beaten into thin leaves like gold.
Copper wire is much employed by bell-hangers and
other artisans. The filings of this metal are used for
giving a green colour to some kinds of artificial fire-works.
Several preparations of copper are employed in medicine,
some of them internally, and others externally;
but most of the former are violently emetic.
Verdigris is a rust or oxide (#21:n21#) of copper, usually
prepared from that metal by corroding it with vinegar.
There is a large manufactory of verdigris at Montpelier
in France. The workmen place alternate strata of copper
plates and husks of grapes, the latter of which
speedily become acid and corrode the metal. The verdigris,
thus formed, is scraped off as it collects on the
surface; it is afterwards dried, and put in bags or casks
for sale. A manufactory of verdigris has lately been
established at Deptford, near London.
A solution of this substance in distilled vinegar affords
permanent crystals, which are improperly called
distilled verdigris, and are made into a green paint.
Verdigris is principally consumed by dyers in combination
with logwood, for striking a black colour. It is
a virulent poison.
Oxide of copper is employed for giving a beautiful
green colour to porcelain. It also imparts the same
colour to glass, and hence is frequently employed for
the formation of artificial emeralds.
.h5
Alloys of Copper.
Of all metals that are known, copper is the most susceptible
// 202.png
.pn +1
of alloy. The most frequent and useful of
these alloys are made with copper and zinc, in different
proportions.
Brass is an alloy composed of three parts of copper,
and about a fourth part of zinc (#241:n241#). It is a beautiful,
useful, and well-known yellow metal. Not being so apt
to tarnish and rust as copper, and being, in other respects,
better adapted for the purpose than that metal,
it is much used for clock-work, and for mathematical
and astronomical instruments. It is more ductile than
either copper or iron, and hence is peculiarly fitted to
be made into wire, for the strings of musical instruments,
and other purposes. Sieves are woven with brass
wire, after the manner of cambric weaving, and of such
extreme fineness that similar ones could not possibly be
made with copper wire. Brass wire, flatted and gilded,
is sometimes made into lace. The finest brass is manufactured
at Geneva. It unites great beauty of colour
to a high degree of ductility; and is used chiefly for
escapement wheels, and other nicer parts of watch-making.
For work in which there is no friction it is
necessary to cover brass with a kind of varnish or laquer,
to improve its colour, and prevent it from being tarnished
by exposure to the atmosphere.
Prince’s Metal, or Pinchbeck, is an alloy containing
three parts of zinc (#241:n241#), and four of copper. This
metal has nearly the same colour as gold, and was formerly
much in use for the manufacture of ornamental
articles of different kinds.
Dutch Gold is formed by the cementation of copper-plates
with calamine (#241:n241#), hammered out into leaves.
This article is chiefly manufactured in Holland and Germany,
and has about five times the thickness of gold leaf.
Bronze, and the metal of which cannons are made, consist
of from six to twelve parts of tin (#238:n238#) combined
with 100 parts of copper. This alloy is brittle, heavier
than copper, and of a yellow colour. Before the method
// 203.png
.pn +1
of working iron was brought to perfection, it was
used by the ancients for the manufacture of sharp-pointed
instruments; and it is supposed to have been
the æs or brass of the Romans.
Bell Metal, or the metal of which bells are formed,
is usually composed of three parts of copper and one of
tin. Its colour is greyish white; and it is very hard,
sonorous, and elastic.
Bronze and bell metal are not, however, always made
of copper and tin only. They frequently have other
admixtures, consisting of lead, zinc, or arsenic. Bell-makers
sometimes abuse the vulgar credulity by pretending
that they add a certain quantity of silver to the
alloy, for the purpose of rendering the bells more melodious:
but they are better acquainted with their business
than to employ so valuable a metal in the operation.
White Copper is an alloy composed of equal parts of
copper and arsenic (#242:n242#). The metal produced by this
mixture is of a whitish colour, but with a coppery tinge.
It is freed from the latter by being melted several times;
and, by this process, is at last rendered as white as silver.
White copper is very brittle; but, if the arsenic
be evaporated by heat, it resumes its ductility, and still
preserves its white colour. When the operation is well
performed, it is easy, at the first glance, to mistake
white copper for silver; but the difference may immediately
be ascertained from the properties inherent to
the two metals.
White copper is employed in the manufacture of
many kinds of trinkets: and of a great number of domestic
utensils; such as tea-pots, coffee-pots, and candle-sticks.
231. MALACHITE is a solid green copper ore, the surface
of which has frequently a bubbled appearance, and the
interior is marked with numerous irregular zones, and layers
of different shades of green. It is somewhat more than three
times as heavy as water, and is so soft as to be easily scratched
by a knife.
// 204.png
.pn +1
In its appearance, malachite somewhat resembles
green jasper; but it is by no means so hard. It is,
however, capable of being cut and polished as a gem,
and is manufactured into various kinds of trinkets,
which of late years have been much in request for necklaces,
brooches, and bracelets. It is also cut into slabs,
and mounted into snuff-boxes. Such is the size of
which it is sometimes found, that M. Patrin saw, at Petersburgh,
a plate of malachite thirty-two inches long
and seventeen inches broad, which was valued at 20,000
livres; but the finest specimens in Europe are some
slabs that are adapted as the tops of tables, sideboards,
&c. at Trianon, in the Park of Versailles: the largest of
these are nearly four feet in length and two feet wide.
They may indeed have been formed by various pieces
joined together; but, if so, the joints are so completely
concealed as not to be discoverable even by the closest
examination. Malachite is sometimes employed for the
engraving of cameos, but is seldom cut in intaglio.
Smaller pieces of this substance, that are used for trinkets,
are about the same value as carnelian. Independently
of its use, in the above respects, and also as an
ore of copper, malachite, when pure, is ground into
powder, and employed as a green pigment.
The Vosges Mountains in Lorraine, and certain copper
mines of Saxony, are celebrated for producing very
fine specimens of malachite. This beautiful mineral is
also found in our own country, in the copper mines of
Cornwall and Wales.
232. TURQUOISE. The beautiful light blue substances
that are called turquoises have usually been considered as the
bones or teeth of animals, impregnated with blue oxide (#21:n21#) of
copper; but they are sometimes found in nodules which are
certainly not of an osseous nature.
Turquoises are frequently set in rings, necklaces,
brooches, and other female ornaments. In Persia they
are very common; and, amongst the Turks, are held in
such estimation that persons of rank almost constantly
wear them in some part of their dress, as ring-stones,
// 205.png
.pn +1
and to adorn the handles of stilettoes. They are imported
into England from Russia, stuck with pitch upon
the ends of straws; because if mixed together in parcels,
the purchaser would not easily be able, in turning
them over, to observe their colour, and ascertain their
value.
In the turquoise there is nothing that can recommend
it to notice except the agreeable softness of its
colour, which is particularly distinguishable by candle-light;
this alone has rendered it so fashionable as an
ornament in female dress, for rings, ear-drops, and
brooches, that the demand for it is at present greater
than the supply. Imitations of turquoise are easily
made in paste, and not unfrequently imposed upon the
ignorant purchaser; but in these, though the colour is
correctly given, there is a glassy lustre much higher
than that of the real stone.
Of late years a spurious kind of turquoise has also
found its way into Europe, which is much softer than
the genuine kind; has more of a green than a blue cast,
and is by no means capable of so good a polish.
233. IRON is a well-known metal, of livid greyish colour,
hard and elastic, and capable of receiving a high polish. Its
weight is nearly eight times as great as that of water.
It is seldom found in a truly native state, but occurs, abundantly,
in almost every country of the world, in a state of oxide
(#21:n21#), and mineralized with sulphuric (#24:n24#), carbonic (#26:n26#), and
other acids.
Iron is found in plants, in several kinds of coloured stones,
and even in the blood of animals.
Of all the metals there are none which, in the whole,
are so useful, or are so copiously and variously dispersed
as iron. Its uses were ascertained at a very
early period of the world. Moses speaks of furnaces
for iron, and of the ores from which it was extracted,
and tells us that swords, knives, axes, and instruments
for cutting stones, were, in his time, all made of this
metal.
The most considerable iron mines at present existing
// 206.png
.pn +1
are those in Great Britain and France. After iron ore is
dug out of the earth, it is crushed or broken into small
pieces, by machinery. It is next washed, to detach the
grosser particles of earth which adhere to it. This operation
ended, it is roasted in kilns, formed for the purpose,
by which the sulphur, and some other substances
that are capable of being separated by heat, are detached.
It is then thrown into a furnace, mixed with a
certain portion of limestone and charcoal, to be melted.
Near the bottom of the furnace there is a tap-hole,
through which the liquid metal is discharged into furrows
made in a bed of sand. The larger masses, or
those which flow into the main furrow, are called
sows; the smaller ones are denominated pigs of iron;
and the general name of the metal in this state is cast
iron.
With us iron is employed in three states, of cast iron,
wrought iron, and steel.
Cast iron is distinguishable, by its properties of being,
in general, so hard as to resist both the hammer and the
file; being extremely brittle, and for the most part, of
a dark grey or blackish colour.
A great number of useful and important articles are
formed of cast iron, such as grates, chimney backs, pots,
boilers, pipes, and cannon shot. These are made by
casting ladles full of the liquid metal into moulds that
are shaped, for the purpose, in sifted sand.
Wrought iron. The process of converting cast iron
into wrought or malleable iron, is called blooming. The
cast iron is thrown into the furnace, and kept melted by
the flame of combustibles which is made to play upon
its surface. Here it is suffered to continue for about
two hours, a workman constantly stirring it, until, notwithstanding
the continuance of the heat, it gradually
acquires consistency, and congeals. It is then taken
out, while hot, and violently beaten with a large hammer
worked by machinery. In this state it is formed
into bars for sale.
The value of iron is beyond all estimate, and infinitely
// 207.png
.pn +1
greater than even that of gold. By means of this metal
the earth has been cultivated and subdued. Without
it houses, cities, and ships, could not have been
built; and few arts could have been practised. It forms
also the machinery by which the most useful and important
mechanical powers are generated and applied.
Steel is usually made by a process called cementation.
This consists in keeping bars of iron in contact with
powdered charcoal, during a state of ignition, for several
hours, in earthen troughs, or crucibles, the mouths
of which are stopped up with clay. Steel, if heated to
redness, and suffered to cool slowly, becomes soft; but
if plunged, whilst hot, into cold water, it acquires extreme
hardness. It may be rendered so hard as even
to scratch glass; and at the same time, it becomes
more brittle and elastic than it was before. Although
thus hardened, it may have its softness and ductility restored,
by being again heated, and suffered to cool
slowly. A piece of polished steel, in heating, assumes
first a straw-yellow colour, then a lighter yellow, next
becomes purple, then violet, then red, next deep blue,
and at last of all bright blue. At this period it becomes
red hot, the colours disappear, and metallic scales are
formed upon, and encrust its surface. All these different
shades of colour indicate the different tempers that
the steel acquires by the increase of heat, from that
which renders it proper for files, to that which fits it for
the manufacture of watch springs. Mr. Stoddart has
availed himself of this property to give to surgical, and
other cutting instruments, those degrees of temper
which their various uses require.
The kind of steel which has been most celebrated in
this country is that imported from Syria under the name
of Damascus steel. Germany is also noted for its steel.
The best steel manufactured in Britain is known by the
name of cast steel; and the making of it, although it
was long kept a profound secret, is now discovered to
be a simple process. It consists merely in fusing it
with carbonat of lime (#140:n140#), or in what is called cementation,
// 208.png
.pn +1
with charcoal powder, in a peculiar kind of furnace.
The iron produced in Sweden is considered superior
to that of any other country in Europe for the
manufacture of steel.
All kinds of edge tools, where excellence is required,
are made of steel; and a steel instrument may be immediately
known from an iron one, by letting fall upon it a
drop of nitric acid or aqua fortis (#206:n206#), somewhat diluted
with water. If it be steel, this will occasion a
black spot; but if it be iron, it will not have this effect.
Steel is attracted by the magnet, and is capable of receiving
a permanent magnetic property, which has led to
the discovery of the mariner’s compass. Had iron been
productive of no other advantages to mankind than this,
it would on this account alone have been entitled to
their greatest attention.
Iron, when exposed to the moisture of the atmosphere,
becomes gradually covered with a brown, or
yellowish substance, known by the name of rust, which,
if suffered to continue without interruption, will corrode
the entire substance of the iron. The rust or oxide of
iron (#21:n21#) is a substance in considerable request by calico
printers for a dye. Iron-moulds are spots on linen
occasioned by its exposure to iron in damp situations;
these are removeable only by the application of an acid.
There are various modes of preserving iron and steel
from rust. The following is recommended by an
eminent French chemist as one of the best. Mix copal
varnish, made greasy with oil, with about four-fifths of
the best spirit of turpentine. Apply this by means of
a sponge, over the whole surface, and allow it to dry.
This varnish may be successfully used for all the metals;
and particularly for the preservation of such philosophical
instruments as, by being brought into contact with
water, are liable to lose their splendour, and become
tarnished.
234. METEORIC STONES are a species of iron ore,
which have at different times been known to fall from the atmosphere.
// 209.png
.pn +1
They have been seen only in shapeless masses, of from a
few ounces to several hundred pounds in weight. Their texture
is granular. They are covered externally with a thin
blackish crust, and are, internally, of an ashy grey colour,
mixed with shining minute particles.
There is sufficient evidence to show that solid masses
of stone have been observed to fall from the air at a
period considerably anterior to the Christian era. Notwithstanding
this, so very extraordinary was the phenomenon,
that, until the year 1802, it was generally regarded
by philosophers as a vulgar error. Mr. Howard,
in that year, submitted to the Royal Society a paper
which contained an accurate examination of the testimonies
connected with events of this kind; and described
a minute analysis of several of the substances
which had been said to have fallen in different parts of
the globe. The result of his examination was that all
these stony bodies differ completely from every other
known stone; that they all resemble each other, and are
all composed of the same ingredients.
The greatest number of the stones which have fallen
from the air have been preceded by the appearance of
luminous bodies or meteors. These meteors have burst
with an explosion, and then the shower of stones has fallen
to the earth. Sometimes the stones have continued luminous
until they sunk into the earth, but most commonly
their luminousness disappeared at the time of the
explosion. Their motion through the air is surprisingly
rapid, in a direction nearly horizontal; but they seem
to approach the earth before they explode. In their
flight they have frequently been heard to yield a loud
whizzing sound. They are hot when they first reach
the earth; and exhibit, on their surface, visible marks
of fusion.
A general tradition has prevailed in almost all ages,
and amongst all people, of the fall of solid bodies from
the atmosphere, under various denominations, but, with
us, more particularly, under that of thunderbolts. In
barbarous and uncivilized countries, these have usually
// 210.png
.pn +1
been ascribed to the miraculous judgment of the deity;
and they may be considered as the true origin of the
worship of stones. The image of Diana, mentioned in
the Acts of the Apostles, as believed by the Ephesians
to have fallen down from Jupiter, and the Palladium or
sacred statue of Minerva, which also is said to have
fallen from Heaven, and to have been preserved in
Troy, as a treasure, on the safety of which that of the
city depended, had each, no doubt, this origin. The
Psalmist evidently alludes to the falling of meteoric
stones, when, speaking of the Almighty, he says, “He
made darkness his secret place; his pavilion round
about him with dark water, and thick clouds to cover
him. At the brightness of his presence his clouds removed;
hailstones and coals of fire. The Lord also
thundered out of Heaven, and the Highest gave his
thunder; hailstones and coals of fire.”
Among numerous other instances of these stones, it
is recorded that, on the seventh of November, 1492, betwixt
eleven and twelve o’clock at noon, a dreadful
clap of thunder was heard at Ensisheim, a considerable
town in Alsace, and that a huge stone was seen to fall
on a field lately sown with wheat. On several of the
neighbours going to the place, the hole it had formed was
found to be about three feet in depth, and the stone when
dug out, weighed two hundred and sixty pounds. It
was preserved in the cathedral of Ensisheim until the
beginning of the French Revolution, when it was conveyed
to the public library at Colmar. There are in
the British Museum two small pieces of this stone, and
fragments of several other meteoric stones which have
fallen in different parts of the world.
Two stones fell near Verona in Italy, in the year
1672, one of which weighed three hundred, and the
other two hundred pounds.
Mr. Sowerby, the publisher of English Botany, and
of several other highly estimable works, possessed a meteoric
stone which fell near Wold Newton in Yorkshire,
in the afternoon of the thirteenth of December, 1795,
// 211.png
.pn +1
and weighed fifty-six pounds. Whilst this stone was in
motion through the air, several persons perceived a body
passing along the clouds, although they were unable to
ascertain what it was. It passed over several different
villages, and was also accurately and distinctly heard.
The day was foggy; and, though there was some thunder
and lightning at a distance, it was not until the
stone fell that an explosion took place which alarmed
all the adjacent country; and created, distinctly, a sensation
that something very extraordinary had happened.
A shepherd belonging to Captain Topham was within
a hundred and fifty yards of the place where it fell;
George Sawden, a carpenter, within sixty yards; and
John Shepley, one of Captain Topham’s farming servants,
was so near that he was forcibly struck by some
of the mud and earth that were raised by the stone
dashing into the ground. In its fall the stone excavated
a place nineteen inches in depth (seven inches of which
were in a solid rock of chalk), and somewhat more than
three feet in diameter, fixing itself so firmly that some
labour was required to dig it out.
Another stone of considerable size fell in Scotland
on the fifth of April, 1704. A misty commotion was
observed in the atmosphere, and, nearly at the time of
the stone falling, a report was heard as loud as if three
or four cannon had been fired at a little distance. The
report was succeeded by a violent rushing or whizzing
noise; and, almost immediately afterwards, the stone
fell into a drain, in the presence of two men and two
boys, splashing the water to a distance of twenty feet
around. The stone, when dug out, was found to have
sunk about eighteen inches into the earth.
On the fifth of November, 1814, about half past four
o’clock in the afternoon, a dreadful peal of thunder was
heard in the Doab in Persia, and was immediately succeeded
by a shower of large stones, many of them from
twenty-six to thirty pounds weight each. Several inhabitants
of the adjacent country were present at the time;
and not fewer than nineteen of the stones were collected.
// 212.png
.pn +1
Professor Pallas, many years ago, discovered lying on
the surface of a hill in Siberia, a mass of native iron,
which weighed 1680 pounds. It was considered by the
natives as a holy relic, and was believed by them to
have fallen from heaven. M. de Bougainville, the
French circumnavigator, discovered, on the banks of the
river La Plata, in South America, an enormous mass of
native iron, which he calculated to have weighed about
100,000 pounds. And a mass of native iron, appearing
in every respect to have been of meteoric origin, was,
some years ago, discovered in the district of St. Jago
del Estro, in South America. It was in the middle of
a great plain, and had no rock nor mountain near it, and
was calculated to have weighed about thirty tons.
The origin of meteoric stones is involved in great obscurity.
Some writers have imagined that they might
be projected from distant volcanoes; others, that they
may have been detached from rocks, and had their substance
considerably changed by a concurrence of natural
causes; others, that they may have been generated
in the air by a combination of mineral substances;
and others, that they may have been projected from the
moon. The latter was the opinion of La Place the
astronomer, who says that a mass, if thrown by a volcano
from the moon, with a velocity of about a mile
and half per second, it will thence be projected beyond
the sphere of the moon’s attraction, and into the
confines of that of the earth; the consequence of
which will be, that the mass must presently fall to
the earth, and become a part of it.
235. LOADSTONE, or MAGNETIC IRONSTONE,
is a compact blackish kind of iron ore, which is possessed of
the power of attracting iron, as well as every substance which
contains ferruginous particles. It is betwixt four and five
times as heavy as water.
This mineral is found in masses of different form and
size in most of the iron mines of Europe and America,
and, when submitted to the furnace, it yields a considerable
// 213.png
.pn +1
proportion of metal. It makes excellent bar
iron, but very indifferent cast iron. In Sweden, and
particularly at Roslager, magnetic iron stone is found
quite pure, and the iron that is wrought from it is imported
in considerable quantities into Great Britain, for
the purpose of being manufactured into steel.
The appellation of load, or leading stone, has been
given to this kind of iron from its magnetic virtues;
for it is not only endowed with the property of attracting
iron, but also of pointing itself, and even enabling a
needle touched with it to point, towards the poles of the
world. We are, however, entirely ignorant what is the
cause of this very extraordinary property.
Artificial magnets, constructed of steel, not only possess
all the essential virtues of the genuine loadstone,
but even in a much higher degree. The natural magnet
is consequently now little esteemed except as an
object of curiosity.
236. PYRITES, or MARCASITE, is a mineral substance,
formed by a combination of iron with sulphur.
It is usually of a bronze, yellow, or brownish colour, very
various in form, being massive, globular, club-shaped, oval,
or crystallized; and so hard as to strike fire with flint.
Few minerals are more common than this, as it occurs,
in some state or other, in almost every rock and
vein. It is often found among coals; and, when
heated, decrepitates with a loud unpleasant noise and
sulphureous smell. To the decomposition of this mineral
it is that the hot temperature of almost all the mineral
waters may be ascribed.
The name of pyrites, which in the Greek language
signifies firestone, has been obtained by this mineral
from its property of striking sparks from steel. It was
formerly used for fire-arms, as we now use flints. In
commerce it is known by the name of marcasite. Some
years ago it was much used, particularly in France, for
the making of buttons and buckles; and was cut and
polished, by lapidaries, for trinkets, particularly for the
rims and hands of watches, and various kinds of female
// 214.png
.pn +1
ornaments. If skilfully cut in the form of small rose
diamonds, although an opaque substance, it has somewhat
the appearance of a diamond. In the tombs of the
Peruvian princes, with whom a considerable portion of
their valuables was always interred, there have been
found polished plates of marcasite, which appear to have
served them as mirrors.
This mineral is never worked as an ore of iron; and
it is principally valued on account of the sulphur which
can be obtained from it by means of heat; and the
green vitriol, or copperas (#208:n208#), which it affords by exposure
to the air.
Ignorant persons frequently mistake iron pyrites for
gold; but it is easily distinguished from that precious
metal by its brittleness. It breaks when hammered,
whereas gold is malleable, or may be extended by hammering:
it also strikes fire with steel, which gold will
not.
237. RED OCHRE, REDDLE, or RED CHALK, is
an iron ore of blood-red colour, which is sometimes found in
powder, and sometimes in a hardened state. It has an earthy
texture, and stains the fingers when handled.
The principal use of red chalk is for drawing: the
coarser kinds are employed by carpenters and other
mechanics, and the finer kinds by painters. For the
latter purpose it should be free from grit, and not too
hard. In order to free it from imperfections, and render
it better for use, it is sometimes pounded, washed,
mixed with gum, and cast into moulds of convenient
shape and size.
Under the name of reddle, this substance is much
used for the marking of sheep; and (when mixed with
oil) for the painting of pales, gates, and the wood-work
of out-buildings.
Another kind of iron ore, or rather a compound of
the ores of iron and manganese, is called umber. This
mineral, which is of a brown colour, is found in beds in
the island of Cyprus, and is used as a kind of paint both
in a raw state and burnt.
// 215.png
.pn +1
238. TIN is a white metal, somewhat like silver in appearance,
but is considerably lighter, and makes a squeaking or
crackling noise when bent. It is very soft and ductile, and
has but little elasticity.
This metal is always found either in a state of oxide (#21:n21#),
or in combination with sulphur and copper; and is about seven
times as heavy as water.
The principal tin mines which are known to us are
those of Cornwall, Devonshire, Germany; the island of
Banca, and peninsula of Malacca, in India; and Chili
and Mexico in America. Of these the most celebrated
are the mines of Cornwall, which are known to have
been worked before the commencement of the Christian
era. Diodorus Siculus, who wrote forty years before
the birth of Christ, gives an account of these mines,
and says that their produce was conveyed to Gaul, and
thence to different parts of Italy. This species of
metal was used in the time of Moses, and is mentioned
in the writings of Homer.
Tin is found in veins, or beds, but chiefly in veins,
running through granite and other rocks. In some of
the valleys and low grounds of Cornwall, the tin ore is
found in rounded grains and masses. In these situations,
small grains of gold are sometimes found with it.
To separate the tin from earthy and other matters
with which it is intermixed, streams of water are passed
over them; and these deposits have the name of stream-works.
When the tin ore has been dug from the earth, or
has been collected at these stream-works, it is thrown
into heaps, and broken to pieces. After this it is
washed, and subsequently roasted in an intense heat,
for the purpose of dissipating some of the substances
with which it is combined. It is lastly melted in a furnace,
and thereby reduced to a metallic state. The
metal is then poured into quadrangular moulds of stone,
each containing about 320 pounds weight. These have
the denomination of block-tin, and are stamped by officers
of the Duke of Cornwall, with the impression of a
// 216.png
.pn +1
lion, the arms of that duchy. This is rendered a necessary
operation before the tin can be offered for sale; and
on stamping, it pays a duty of four shillings per hundred
weight to the Prince of Wales, as Duke of Cornwall,
who thence derives a very considerable income.
The article usually called tin, or tin-plate, and, in
Scotland, white iron, of which saucepans, boilers, drinking
vessels, and other utensils of domestic economy are
made, consists only of thin iron plate coated with tin.
It is thus formed. The iron plates are immersed in
water rendered slightly acid by spirit of salt (muriatic
acid, 202) or spirit of vitriol (sulphuric acid, 211): after
which, to clean them completely, they are scoured quite
bright. These plates are then each dipped into a vessel
filled with melted tin, the surface of which is covered
with suet, pitch, or resin, to prevent the formation of
dross upon it. The tin not only covers the surface of
the iron, but completely penetrates it, giving to its
whole substance a white colour.
In a manner similar to this, stirrups, buckles, bridle-bits,
and other articles, are tinned.
Iron is usually tinned before, but copper always after
it has been formed into utensils. The object to be attained
by the tinning of copper is to prevent the vessels
made of that metal from being corroded, and to preserve
the food prepared in them from being mixed with any
particles of that poisonous substance called verdigris,
which is formed by such corrosion. In the tinning of
copper vessels, their interior surface is first scraped very
clean with an iron instrument, and then rubbed over
with sal-ammoniac (#207:n207#), for the purpose of more completely
cleansing them, and also of preventing the formation
of verdigris from the copper during the operation.
The vessel is then heated, and a little pitch is
thrown into it. While quite hot, a piece of tin is applied
to the copper, and this, instantly uniting with it,
soon clothes the whole surface with tin.
This metal, when amalgamated with mercury, is used
for the silvering of looking-glasses (#228:n228#). When tin is
// 217.png
.pn +1
melted in an open vessel, its surface is soon found to be
covered with a grey powder, which is an oxide (#21:n21#) of
the metal, and is generally called dross. If the heat
be continued, the colour of this powder becomes yellow.
In this state it is known by the name of tin-putty, and
is employed in polishing glass, steel, and other hard substances.
When the heat is very violent, the metal
takes fire, and is converted into a fine white oxide,
which is used to render glass opaque, for the forming of
enamel. Oxide of tin is also an important article to
dyers. It is employed by them, in large quantities, to
give brightness to such colours as are used in forming
scarlets and other reds: and to precipitate the colouring
matter of other dyes.
Tin is an essential ingredient in bell-metal, bronze,
pewter, and various other compounds. It may be combined
with lead, in any proportion, by fusion; and this
alloy is harder, and possesses much more tenacity than
tin. The hardest alloy is a composition of three parts
of tin and one of lead. The presence of the tin destroys,
in a great measure, the noxious qualities of the lead. It
is sometimes customary to tin copper vessels with this
mixture, and it has been ascertained that such vessels
are in no respects injurious.
There are three kinds of pewter in common use.
These are called plate, trifle, and ley pewter. The first,
which is made into plates and dishes, is formed of tin,
with a small proportion of lead and antimony (#245:n245#).
The second, or trifle pewter, which is made in somewhat
different proportions, is used for the quart and pint pots
of the publicans: and the ley pewter, which is formed of
three parts of tin and one of lead, is manufactured into
wine and spirit measures.
Tin may be beaten into leaves or plates that are much
thinner than paper. But, when it is thus worked, several
leaves must be joined together. They then support
each other, and yield to the hammer without
tearing. These leaves are used for the silvering of glass
globes, and the plating of other metals. Those that are
// 218.png
.pn +1
used for the silvering of looking-glasses are much
thicker. The article called tin-foil is an alloy, consisting
generally of two parts of tin and one of lead; and
capable of being beaten to less than the thousandth
part of an inch in thickness.
239. LEAD is a heavy metal, of pale and livid grey colour
when broken, not sonorous when pure, very flexible, and so
soft that it may be marked with the nail. It stains paper or
the fingers of a bluish colour, and is about eleven times heavier
than water.
The most common state in which lead is found is in combination
with sulphur and a small portion of silver. This ore
is known by the name of galena, and is frequently in the form
of blackish cubical crystals. Lead is also found in union with
arsenic (#242:n242#) and many acids.
Great Britain possesses the most important lead-mines
in the world; and those that are best known are
in the counties of Flint and Derby. The latter are
supposed to have been worked even in the time of the
Romans.
Lead mines are entered sometimes by perpendicular
shafts, and sometimes (when in the sides of hills) by
levels. In some of the Derbyshire mines, where the
depth of the veins will admit of it, the men work, at
different heights, of from four to six feet above each
other, along what are called stoops; the uppermost
men being two or three yards before those next in
succession, and thus forming a kind of steps. The
implements used are picks, hammers, and strong iron
wedges; and the rocks are also frequently loosened by
means of gunpowder.
When the ore is brought out of the mine, it is sorted
and washed, to free it from dirt and rubbish. After
this it is spread on a board; the best pieces are picked
out and separated; and those containing ore mixed with
spar (#194:n194#) or other substances, are placed separate, to
be broken, and again picked. After the ore, by pickings
and washing, has been sufficiently cleansed from extraneous
matters, it is roasted in a kind of kiln to free
// 219.png
.pn +1
it from the sulphur that is combined with it. The next
process is to mix it with a certain quantity of coke,
charcoal, or peat, and submit it to the smelting furnace.
In this furnace there are tap-holes, which, when the
lead is melted, are opened, and the metal, in a fluid
state, runs into a large iron pan. The dross which
floats on its surface is now skimmed off; and the metal
is taken out by ladles, and poured into cast iron moulds,
with round ends. The lead thus formed, is ready for
use, and has the name of pig lead. According to their
size, the pieces that are thus cast have the appellation
of pigs, and half-pigs.
Lead is mentioned in the Sacred Writings; and is
described by Homer as in common use at the period of
the Trojan war. The ancients seem to have considered
it as nearly allied to tin. The Romans employed it to
sheathe the bottoms of their ships, fastening it to the
planks and timbers by nails made of bronze.
When first melted, lead is bright, but it soon tarnishes
by exposure to the air. It melts at a temperature very
low in comparison with most other metals; and when a
strong heat is applied, it boils and evaporates.
Lead is much employed in the useful arts. When
rolled between iron cylinders to a requisite state of
thinness and uniformity, it is used for the covering of
houses and churches, notwithstanding the danger, in
case of fire, to persons within, who are exposed to a
shower of burning metal. It is cast into pipes, cisterns,
and reservoirs for water, as well as into large boilers
for chemical purposes. But all culinary or domestic
vessels made of lead, particularly if intended for the
keeping of acid liquors, should carefully be avoided, as
the surface of the lead is thereby corroded, and the
liquid contained in them is rendered poisonous. Hence
arises that dreadful complaint, too well known where
cyder is kept in leaden cisterns, called the Devonshire
colic; hence also the injury which sometimes follows
from the use of lead in the glazing of coarse earthenware.
// 220.png
.pn +1
Great quantities of lead are consumed for the making
of shot. For this purpose the metal is alloyed with
arsenic (#242:n242#), to render it more brittle; and to render
the grains more round and perfect than they otherwise
would be. Shot is formed by dropping the melted
alloy into water, through an iron or copper frame, perforated
with round holes, according to the size required.
For the smallest shot the elevation is about ten feet
above the water; and for the largest about a hundred
and fifty feet.
An alloy of lead and tin, in the proportion of two
parts of lead and one of tin, forms the solder which is
used by plumbers. The types that are used by printers
for very large characters are sometimes composed of
an alloy of lead and copper. Lead is also used, with
tin, in the manufacture of pewter.
.sp 2
.h5
Oxides of Lead.
The different oxides (#21:n21#) of lead are easily soluble in
oil, and consequently are of great use to painters. Of
these the following are the most important:
White Lead, or Ceruse.—This is made by suspending
thin plates of lead over heated vinegar, in such manner
that the vapour which rises from the acid may circulate
about the plates. By this process the plates become at
length entirely corroded, and converted into a heavy
white powder. The manufacture of white lead is a
most unhealthy trade, and is confined to a few persons,
who have large conveniences for the purpose. This
substance, when mixed with oil, is used as a paint for
wood-work both of the outsides and insides of buildings.
The fumes that are emitted from white paint are extremely
noxious. Persons who breathe them are frequently
seized with pains, and experience symptoms not
much unlike those that precede palsy; and the danger
which attends the inhabiting of apartments recently
painted is well known. The odour of vinegar will correct
the pernicious effect of these exhalations, by acting
// 221.png
.pn +1
as a solvent, and combining with, and precipitating
them. We are informed that white lead, dangerous as
it is, was in great request among the Roman ladies as
a cosmetic. It is sometimes used as an external application
for ulcers and other kinds of sores.
Massicot is a mineral substance of yellow colour,
used for painting, and prepared from the dross or
pellicle that is formed by the melting of lead.
Red Lead, or Minium, is a mineral substance of red
colour, used for painting, and made, by a tedious and
troublesome process, from massicot. For this purpose
the massicot is ground to a fine powder, put into a
furnace, and constantly stirred, whilst the flame of the
burning coals plays against its surface for about forty-eight
hours, when it is converted into a red powder,
which is the article under consideration. It is subsequently
passed through very fine iron sieves. The use
of red lead as a pigment is well known; but as it is
liable to turn black, vermilion is generally preferred to
it. It is sometimes employed in medicine as an external
application for abating inflammations, for cleansing
and healing ulcers, and the like; and is used in the
manufacture of glass.
Litharge is another kind of oxide of lead. This is
prepared by exposing calcined lead to a brisk fire for a
certain length of time. The substance, on cooling,
concretes into a flaky matter. Litharge is used by
potters for the glazing of earthenware, but vessels that
are glazed with it are thereby rendered unwholesome.
It is also employed, in the composition of the finer
kinds of glass, for the purpose, not only of giving
them greater transparency, but also of rendering them
capable of sustaining sudden changes from heat to
cold, and of giving to them a susceptibility of being
cut without breaking. It, however, adds considerably
to the weight of the glass.
Litharge Plaster, or Diachylon Plaster, as it is more
frequently called, is prepared by boiling two pints of
olive oil with one pint of litharge, adding water, and
// 222.png
.pn +1
constantly stirring the mixture till they are duly incorporated.
This plaster is applied in excoriations of the
skin, slight wounds, and other sores.
Sugar of Lead is a preparation either from the metal
itself, or from white lead and distilled vinegar. It is
usually observed in the form of small slender crystals,
which have a glossy appearance like satin. This substance
is employed, in considerable quantity, by dyers
and calico printers; and is the basis of a liquid frequently
used in medicine, called Goulard, or Goulard’s
Extract. Although in itself a most virulent poison, it
is often used by unprincipled dealers for correcting the
rancidity of oil of almonds and olive oil; and a similar
pernicious fraud is practised by dissolving a portion of
it in wines which are becoming acid, in order to correct
their acidity. These frauds, however, are easily detected
by preparations or tests, which are sold by chemists
for that purpose. Perhaps the best and simplest
test is Harrowgate water: a little of this poured into the
suspected compound will discover the presence of lead
by giving to the fluid a dark brown or blackish tinge.
The following is a pleasing experiment. Dissolve an
ounce of sugar of lead in about a quart of water; filter
the solution through a piece of blotting paper, and put
it into a glass decanter, suspending in it a piece of zinc
by a brass wire. A decomposition will take place; the
lead will be set at liberty, and will attach itself to the
zinc, forming there a sort of metallic tree.
.tb
It has been stated that silver is usually a component
part of lead ore. To disengage this, where the quantity
is sufficient to repay the expense, the lead, after it has
been smelted, is subjected to the action of what is called
a refining furnace. A continued blast of fresh air is
thrown upon its surface by means of large bellows,
while the lead is kept in a state as intensely hot as possible.
This by degrees converts the lead into a yellow
scaly oxide or dross. The oxide, thus formed, is driven
off from the melted metal as it rises, and the silver is
// 223.png
.pn +1
left alone at the bottom, in a metallic state. After
the operation is complete, the oxide is fused with charcoal,
and again reduced to metallic lead.
.tb
We must not omit to mention that, in some of the
mines of Derbyshire, there is a singular variety of lead
ore called slickenside. This is a kind of galena, which
presents, to the eye, a smooth and bright surface, appearing
as if it were plated. Sometimes it forms the
sides of cavities; and it has the extraordinary property,
when merely pierced with the miner’s tool, of rending
with great violence, and exploding with a crackling
noise. Some miners, fearless of danger, venture to
scratch it with their tools; and, on coming again to the
spot, they often find that, during their absence, the
slickenside has exploded, and fallen off in considerable
quantity. Sometimes, however, they suffer for their
imprudence. Mr. Mawe, in his account of the Mineralogy
of Derbyshire, says, that he has seen a man
come out of a mine cut violently, as if he had been
stabbed about the neck and in other parts of the body,
in consequence of the explosion of slickenside which
he had pierced. The cause of this extraordinary
phenomenon has not been explained.
240. NICKEL, when pure, is a fine white metal, somewhat
resembling silver in appearance, but it is attracted by the
magnet, and has itself the property of attracting iron.
It is ductile and malleable, difficult of fusion, and about
nine times heavier than water. This metal is always mixed
with arsenic (#242:n242#) and iron.
Nickel is found in Cornwall, and in some other
counties of England; in Germany, Sweden, France,
Spain, and several parts of Asia. The Chinese employ
it in making white copper; and, in conjunction with
copper and zinc, they manufacture it into various kinds
of children’s toys. Nickel gives a certain degree of
whiteness to iron. It is used, with advantage, by some
of the Birmingham manufacturers, in combination with
that metal, and by others in combination with brass. If
// 224.png
.pn +1
it were possible to discover an easy method of working
nickel, there can be little doubt but it would be found
a very valuable metal for surgical instruments, for
compass needles, and other articles, as it is not, like
iron, liable to rust. When nickel is freely suspended,
it points to the north and south, in precisely the same
manner as the common magnetic needle.
Oxide of nickel is used for giving colours to enamels
and porcelain. In different mixtures it produces brown,
red, and grass-green tints.
241. ZINC, or SPELTER, as it is sometimes called, is a
bluish white metal formed in thin plates adhering together.
It has a very perceptible taste, is about seven times heavier
than water, rather harder than silver; and possesses but a
small degree of malleability and ductility, except under certain
circumstances.
This metal is never found in a pure state; and the principal
ores from which it is procured are known by the names of
Calamine and Blende. Of these the former is an oxide (#21:n21#)
of zinc combined with carbonic acid (#26:n26#), and the latter is a
combination of zinc with sulphuric acid (#24:n24#).
The ores of zinc are very abundant in many countries.
We are informed that nearly the whole of Flintshire
in North Wales abounds with calamine; and that,
so entirely ignorant were the inhabitants of its use, as,
till after the middle of the eighteenth century, to have
even mended their roads with it. These roads, however,
have since been turned up in many places, and the materials
have been converted to more valuable purposes.
Derbyshire affords a great quantity of the ores of zinc,
particularly calamine. This is found at various depths,
generally in beds of yellow, or reddish brown clay, and
usually near some vein of lead ore.
The mode of extracting zinc from its ore is by distillation.
The process adopted, in some parts of Saxony,
is equally simple and ingenious. An inclined stone is
placed near the anterior part of a furnace, in which the
ore of lead containing zinc is fused. A great part of
the zinc condenses upon this stone, and flows, in
// 225.png
.pn +1
drops or globules, into a quantity of charcoal placed at
the bottom to receive it. These globules are afterwards
again melted, to run the metal into a mass.
When exposed to the air, the surface of zinc is soon
tarnished, but it scarcely undergoes any other change.
It has a certain degree of ductility. When heated a
little above 218° of Fahrenheit, it is malleable; and,
when annealed, may be passed through rollers, and
formed into thin sheets or leaves. Although, previously
to being thus heated, it is brittle; on now
cooling, it continues soft, flexible, and ductile. The
inconvenience arising from the brittleness of the zinc
being removed, this metal is applicable to many useful
purposes. It may even be drawn into wire, but the
tenacity of this is not great: a piece of zinc wire, one
tenth of an inch in diameter, will sustain only a weight
of twenty-six pounds without breaking. It has been
proposed to substitute zinc in the place of tin for the
lining of copper vessels; but it has not hitherto been
ascertained whether this can be done with effect, and
without injury. Prizes have of late been offered, to a
considerable extent, in France, for the ascertainment
of this fact. In China, zinc is employed as a current
coin of the country; and for this purpose it is used in
the utmost purity. The Chinese also, as well as the
artists of our own country, employ it to a great extent
in various alloys. It is used in the manufacture of
brass, pinchbeck or prince’s metal, and bronze, all of
which consist of this metal in combination with different
proportions of copper (#230:n230#). Tutenag is a well known
white metal, made principally of zinc, and used for
forming candlesticks and other articles. When tutenag
is well manufactured, it is of good colour, and not more
disposed to tarnish than silver. Zinc is one of the metals
employed to form the galvanic or voltaic apparatus;
and its filings are mixed with gunpowder, to produce
those brilliant stars and spangles which are seen
in the best kinds of artificial fire-works. Preparations
of zinc are occasionally used in medicine. If a thin
// 226.png
.pn +1
plate of zinc be applied to the upper surface of the
tongue, and a shilling to the lower surface, and both
metals, after a little while, be brought into contact, a
very peculiar taste will, at that instant, be perceived.
The same sensation will be perceived, though in a
weaker degree, if the silver be placed at the top and
the zinc at the bottom.
If a silver probe be introduced high up one of the
nostrils, and be brought into contact with a piece of
zinc placed on the tongue, a sensation not unlike that
of a strong flash of light will be produced in the corresponding
eye. A similar perception will result, both
at the moment of contact and that of separation, if one
of the metals be applied as high as possible between
the gums and upper lip, and the other in a similar situation
with the under lip, or even under the tongue.
A white oxide (#21:n21#) prepared from zinc, was, some
years ago, proposed as a substitute for white lead in
house painting. This oxide is not dangerous in its
application; and does not become yellow when mixed
with oil. But these advantages are counterbalanced
by some defects, which have hitherto caused it to be
rejected. It is lighter than white lead: does not cover
the surface so equally, nor so well; and is of considerably
higher price.
Calamine.—The principal use of calamine is in the
manufacture of brass (#230:n230#); and the mines of Derbyshire,
and of Limbourg in the Netherlands, supply with
this mineral nearly all the brass works in Europe.
After the calamine is dug out of ground, it is reduced
to pieces not in general larger than a nut. It is then
roasted for five or six hours, in what is called a reverberating
furnace. The large pieces are separated, and
the small ones are passed through a sieve. It is
washed; and, when dry, is ground in a mill. In this
state it is sold. The principal demand for it is at
Birmingham, for the different brass founderies in that
town.
The use of calamine in the composition of brass was
// 227.png
.pn +1
known at a very early period. It is mentioned by
Aristotle, who also makes a distinction between the
compound resulting from the mixture of copper and
calamine or brass, and that resulting from the mixture
of copper and tin or bronze.
.sp 2
.pb
.sp 4
.h4
ORDER II.—BRITTLE METALS,
.sp 2
.fs 85%
.in 2
.ti -2
OR SUCH AS ARE NOT CAPABLE OF BEING FLATTENED
OR ELONGATED BY THE HAMMER WITHOUT TEARING
OR BREAKING.
.in 0
.fs 100%
242. ARSENIC, in a metallic state, has a bluish white
colour, and considerable brilliancy; it is remarkably brittle,
is the softest of all known metals, and is somewhat more than
eight times heavier than water.
It is found nearly pure, and in considerable abundance, in
different parts of Germany; usually occurring in masses of
various shapes, and in combination with a small portion of
iron, gold, or silver.
The arsenic sold in the shops, and too well known for its
poisonous qualities, is an oxide (#21:n21#) of this metal artificially
prepared.
In some mines on the Continent arsenic is very
abundant, and is found extremely injurious to the
workmen. Being very volatile, its fumes affect and
destroy the lungs, and occasion death in a short time
to many of them. One of its ores, arsenical pyrites, is
found abundantly in Cornwall and Devonshire, accompanying
ores of copper and tin; and, in combination
with other metals, it occurs, in a greater or less proportion,
in almost all mines.
Arsenic is occasionally used in the arts. It is employed
in various metallic combinations where a white
colour is required, and, particularly, for the whitening
or bleaching of copper, which is thereby also rendered
// 228.png
.pn +1
capable of taking a fine polish; hence its use in many
of the compositions for the mirrors of reflecting telescopes,
and for other optical instruments. The manufacturers
of glass frequently employ the oxides of
arsenic in the fabrication of that article. Arsenic is
used in the processes of dyeing and calico printing;
and for the imparting of different artificial shades and
colours to furs. It is also used in the manufacture of
small shot, from its rendering the lead more brittle, and
better capable of being formed into grains, than it
would be without such admixture.
The arsenic of commerce is prepared to a great extent
in Bohemia and Saxony, by roasting cobalt ores
for the manufacture of zaffre (#247:n247#). White arsenic is
made, by mixing the common oxide with potash, and
submitting it to a certain degree of heat, in vessels
adapted to the purpose; the arsenic, rising in fumes, is
separated, leaving the sulphur behind, united to the
potash. This process is called sublimation.
Of all substances with which we are acquainted this
is perhaps the most deadly. If only a few grains of it
be taken into the stomach, it proves fatal; and it has
frequently proved the more injurious from its deceitful
appearance, in which it somewhat resembles salt or
white sugar. Carelessly left in places open to the
access of children, arsenic has not unfrequently been
mistaken by them for sugar, and has been attended
with the most dreadful consequences. If thrown on
heated coals, however, it is immediately known, by
the smell of garlic, and the white fumes which it
gives out. The best remedy for this poison is said to
be a few scruples of liver of sulphur (sulphuret of
potash), dissolved in half a pint or a pint of water, and
administered a little at a time, as the patient can
bear it.
Notwithstanding its deleterious qualities, arsenic is
occasionally used in medicine, though in extremely
small doses; and it has, in particular, been found
efficacious in many cases of intermittent fever.
// 229.png
.pn +1
It is employed as a poison for rats and mice; and,
diluted with water, it attracts and poisons flies, whence
it is sometimes called by the French, poudre a mouches.
There cannot, however, be too great caution used
either in the preparation, or in the application, of this
fatal poison.
243. YELLOW ORPIMENT is a mineral substance of
lemon colour, which consists of arsenic in combination with
sulphur; and in the proportion of about fifty-seven parts of
the former and forty-three of the latter.
It is about thrice as heavy as water; and is found both in
a massive and crystallized state; but the crystals are so confused
that their figures cannot easily be determined.
The orpiment of commerce is an artificial production,
and is chiefly imported from different parts of the
Levant. The Turks, and other Orientals, use it in the
depilatories which serve to render bald the top of the
head. A very beautiful, but fugitive pigment, called
King’s yellow, is prepared from this mineral; and other
preparations of orpiment are occasionally used by
painters, and also by dyers and calico printers. The
whole of these, however, are extremely poisonous.
Orpiment is found in a natural state, along with copper
and other ores, in Natolia, Servia, Hungary,
Turkey, and some other countries.
244. REALGAR, or RED ORPIMENT, is a mineral
substance of red or orange colour, which consists of arsenic in
combination with sulphur; and in the proportion of seventy-five
parts of the former, and twenty-five of the latter.
It is somewhat more than three times as heavy as water;
and occurs sometimes in a crystallized, and sometimes in a
massive or disseminated state.
This production, which, by ignorant persons, is not
unfrequently mistaken for red lead, is in considerable
request by painters, dyers, and calico printers. In China
it is manufactured into small pagodas and other ornaments.
And the Chinese form it into medical cups,
and use lemon juice which has stood for some hours in
// 230.png
.pn +1
them, as a cathartic. Realgar is poisonous, but by no
means so much so as arsenic (#242:n242#).
It is found in Sicily, Hungary, and various parts of
Germany: and is very common in several districts of
China.
245. ANTIMONY is a compact metallic substance of
brilliant and slightly bluish white colour, destitute of ductility,
and about seven times heavier than water.
Its texture is laminated, the plates crossing each other in
almost every different direction. It is as hard as silver, and
so brittle that it may easily be reduced to powder, in a mortar.
In the state of the Connecticut, North America, it
is said that antimony, in a pure metallic form, is found
in such abundance that, in some places, large masses
of it may be seen lying on the surface of the ground.
The principal supply of antimony in Europe is from an
ore which is found in Hungary and Norway, called
sulphuret of antimony. The process of bringing it
into a state for use is very simple. The mineral is put
into pots, each of which has a hole in the bottom, and
which is placed on another pot bedded in the earth.
The upper pots, which are filled with the mineral, are
heated. As soon as the antimony is fused it flows into
the lower pots, while the substances with which it was
combined remain in the upper ones. The antimony
fixes, and forms cakes of the shape of the pots which
receive it. In this state the metal presents, in its fracture,
a surface thick-set, with long needle-shaped crystals,
which, lying by the side of each other, compose,
as it were, the whole of the mass. It is afterwards re-melted
and cast into cakes for sale.
This metal, in a pure state, or alloyed only with a
very small portion of silver and iron, is found in veins of
mountains in some parts of France and Sweden, occurring
in massive and kidney-shaped lumps of white
colour.
The only mine of antimony in Britain, which is of
any importance, is at Glendinning in Dumfries-shire. It
was discovered in 1760, in searching for lead ore, but
// 231.png
.pn +1
was not regularly worked till 1763. In the first five
years about a hundred tons’ weight of antimony were
obtained from it. This at 84l. per ton, produced the
sum of 8400l. The undertaking was afterwards relinquished,
but, as the price of antimony is now at least
thrice what it then was, it is supposed that this work,
if resumed, might prove an advantageous speculation.
The vein of ore is only from eight inches to a foot and
a half in thickness.
Antimony was known to the ancients. The earliest
account we have of it is in the Sacred Writings. The
passage in the Second Book of Kings,[#] which states
that, on the approach of Jehu to the city of Jezreel,
“Jezebel painted her face,” implies, in the original,
that she stained her eyes and eyebrows with antimony,
for the purpose of making them look black and large,
a custom which, at that period, was prevalent in several
of the Eastern countries. Antimony was likewise considered
by the ancients a remedy against inflammations
of the eyes.
This metal is the basis of many of the officinal preparations
which are now in use; and it was the basis
of many others which were formerly used, but are now
discontinued. No mineral substance has so much attracted
the attention, or so much divided the opinion
of physicians, as antimony. One party extolled it as
an infallible specific for almost every disease; whilst
another described it as a virulent poison, which ought to
be expunged from the list of medicines. It was on this
metal that the alchemists of the middle ages principally
founded their hope of discovering the philosopher’s
stone; and, by a kind of good fortune, of which we
can cite but few examples, it has happened that, in
pursuing a chimera, they hit upon a succession of important
realities. To the unremitted perseverance with
which they tormented this metal, if we may so express
it, the art of healing has been most essentially indebted.
.pm fn-start // A
Ch. ix. v. 30. See also Ezek. Ch. xxiii. v. 40.
.pm fn-end
// 232.png
.pn +1
The first rational account of the properties of antimony
was given, about the end of the seventeenth century,
by a French chemist, whose name was Lemeri.
Its great importance in medicine will be seen by an
enumeration of some of the most valuable preparations
of it which are still in use.
Antimonial Wine is prepared from antimony, in conjunction
with white Lisbon wine. It is employed as an
emetic; but, if mixed with milk, this quality is said to
be completely destroyed, and it becomes narcotic.
Emetic Tartar, which is much more employed in this
country than all the other antimonial preparations put
together, is formed from antimony mixed with its own
weight of tartar, and a certain proportion of water,
and afterwards boiled, filtered, and suffered to crystallize.
Butter of Antimony is obtained from a combination
of antimony with corrosive sublimate. It is denominated
by chemists muriat of antimony, and is usually a
thick fatty mass of greyish white colour.
Glass of Antimony is a vitreous substance of reddish
brown colour, which is occasionally used in medicine,
but more frequently in colouring the imitations of yellow
diamond, Oriental, Brazil, and Saxon topaz,
hyacinth, emerald, and beryl.
James’s Powder, or Antimonial Powder, is a well-known
medicine, composed of phosphat of lime and
antimony.
An alloy consisting of sixteen parts of lead and one
part of antimony constitutes the metal of which printers’
types are formed. This alloy does not differ from
lead except in being considerably harder and more
tenacious. The plates on which music is engraved
are formed of a mixture of tin and antimony; and
the oxides of antimony are used for the colouring of
glass.
246. BISMUTH is a reddish white semi-metal, harder
than silver, and composed of broad brilliant plates adhering
together.
// 233.png
.pn +1
It is nearly ten times heavier than water, and is so brittle
as readily to break under the hammer. None of the semi-metals
are so easy to be fused as this; it melts even in the
flame of a wax candle, and long before it becomes red hot, and
has the singular property of expanding as it cools.
The ores of bismuth chiefly occur in Sweden, Norway,
Germany, France, and England. This metal
appears to have been known to the ancients. It was
confounded by them with tin; and, even in our own
manufactories, it is known to the workmen by the name
of tin-glass.
It is not of much use in the arts; but its fusibility
renders the working of it very simple and easy. It is
employed in the composition of some of the soft kinds
of solder; and is also used for giving hardness to tin
and other metals. Amalgamated with mercury it renders
that metal less fluid; and the addition of it to
mercury and tin is found useful in the foliating or silvering
of looking-glasses. Some manufacturers use it
in the composition of pewter; but it is said that this
ought not to be done, particularly for the formation of
vessels intended to contain food, as bismuth partakes of
the noxious properties of lead, and sometimes contains
even arsenic. It is also occasionally employed in
the fabrication of printers’ types.
A very singular metal is formed by melting together
eight parts of bismuth, five of lead, and three of tin.
Tea-spoons formed of this metal surprise all who are
unacquainted with their nature: they have somewhat
the appearance of common spoons, but they melt as
soon as they are put into boiling water.
Bismuth reduced to powder, mixed with the white
of eggs and applied to wood, gives it, when gradually
dried and rubbed with a polisher, the appearance of
being silvered. If this metal be dissolved in aquafortis
(#30:n30#), and water be poured into the solution, a white
powder precipitates, which is an oxide of bismuth, and
which, after being well washed, is used as a pigment,
under the name of pearl-white. From its beautiful appearance,
// 234.png
.pn +1
this powder is sometimes employed by ladies
for painting their skin; a practice which cannot be too
much condemned, both on account of the danger with
which it is attended, and from its soon injuring both the
texture and natural colour of the skin. It has the further
disadvantage of turning black when touched by the
fumes of fetid and other substances; and ladies, who
have used this cosmetic, and have afterwards bathed
in the Harrowgate waters, have come from the bath a
perfectly tawny colour. It was probably the oxide of
bismuth which the Roman ladies used for whitening
their skin; for Martial, in speaking of a lady, who
made too free an use of cosmetics, describes her as
afraid even of the sun. The oxide of bismuth is used
in the composition of most of the pomades employed in
France for painting the face.
A preparation of bismuth has lately been employed
in medicine, as a remedy against spasmodic affections
of the stomach.
The following is a pleasing experiment, illustrative
of metallic crystallization. Melt a ladleful of bismuth,
and allow it to cool slowly and quietly till a thin crust
is formed on the surface: then, with a pointed iron,
make two small opposite apertures through the crust:
and, through one of these, quickly pour out the fluid
portion, as carefully and with as little motion of the
mass as possible. The air having entered by the other
aperture, there will appear, on removing the upper
crust by means of a chisel, when the vessel has become
cold, a cup-shaped concavity, studded with very brilliant
crystals, and more or less regular according to the
quantity of metal employed, the tranquillity and slowness
with which it has cooled, and the dexterity with
which the fluid portion of the mass was poured off before
it became solid. The same effect may be produced
by melting bismuth in a crucible which has a hole in
the bottom, lightly closed by an iron rod or stopper;
this is to be drawn out when the mass begins to congeal.
// 235.png
.pn +1
By so doing, the upper portion, which is fluid,
is made to run off, and a cake studded with crystals
will be left.
.sp 2
.fs 85%
247. COBALT is a semi-metal of grey colour with a shade
of red, brittle, somewhat harder than silver, nearly eight times
as heavy as water, is attracted by the magnet, and is itself
capable of being rendered permanently magnetical.
.fs 100%
The ores of cobalt are not numerous, and are, for the most
part, combinations of this substance with other metals, or of
its oxides (#24:n24#) with arsenic, or with sulphuric acid (#21:n21#).
The name of this metal implies an evil being, (Kobold,
German, goblin) and is said to have been given on account
of the vapour of arsenic, which issues from it,
tormenting the miners, and making them believe that
they are afflicted by wicked spirits. Hence it was once
customary in Germany to introduce into the church
service a prayer that God would preserve miners and
their works from cobalts and spirits.
Cobalt is found in several parts of Europe, but most
plentifully in the southern borders of France, and in
Saxony; and the cobalt ores of Hesse, although they
were formerly used for no other purpose than the
mending of roads, are said now to yield a clear profit of
nearly 15,000l. a year. Some parts of our own country
yield this substance in considerable abundance, particularly
the Mendip Hills in Somersetshire, and a mine
near Penzance in Cornwall.
After the ore is taken from the earth, it is broken
into pieces about the size of a hen’s egg, and the stony
parts are picked out. The sorted mineral is then
pounded in mills, and sifted through brass-wire sieves.
The lighter particles are next carried off by water.
After undergoing some other preparations, to rid it
of the impurities and foreign matters with which it is
connected, it appears in the form of a dark grey oxide.
The working of the cobalt ores in Germany is considered
so injurious, on account of the arsenic with
which they are combined, that much of the labour is
// 236.png
.pn +1
performed by criminals who are condemned to it for
the commission of crimes which, by the laws of the
country, have deserved the punishment of death.
As a metal, cobalt was unknown till the year 1733,
when it was discovered by a celebrated Swedish chemist
whose name was Brant. In its metallic state it is not
employed in the useful arts; but in a state of oxide it
is found extremely valuable in the colouring of porcelain,
in painting, enamelling, and for other purposes.
Cobalt and ultramarine form the most permanent
blue colours with which we are acquainted. The old
painters generally used them for the representation of
the sky and of blue drapery, and this is the reason why
these parts in some old pictures have been found so
much more durable than any others.
Zaffre is an oxide of cobalt mixed with about three
times its own weight of calcined and pounded flint.
It has been chiefly imported into this country from
Saxony and Bohemia, but it is now also manufactured
from cobalt dug from mines in the Mendip Hills and
in Cornwall. In Staffordshire there are several persons
who carry on a considerable trade in preparing this colour
for the earthenware manufacturers of that county.
This substance is extremely valuable for the colouring
of porcelain and glass; as it resists without
change, the effects of the most intense heat. Hence
also it is advantageously used for giving various shades
of blue to enamels, and to glass manufactured in imitation
of lapis lazuli, turquoise, sapphire, and various
precious stones. So intense is the colour imparted by
it that a single grain of zaffre will give a full blue tint
to 240 grains of glass.
Smalt is a kind of glass, of dark blue colour, formed
by melting zaffre with three parts of sand and one of
potash; when this substance is ground to a coarse
powder, it has the name of strewing-smalt, and is much
used by sign painters, as an ornamental filling up of the
vacant space betwixt the letters of signs. In Germany
it is frequently employed instead of sand for the purpose
// 237.png
.pn +1
of drying ink after writing. The same substance reduced
to a perfectly fine or impalpable powder, is the
article which is sold under the name of powder-blue,
and which is not only used by laundresses and others
in the getting up of linen, but also as the basis of
several kinds of paint; and by the manufacturers of
writing and printing papers, to give a blue tinge to
those articles.
A solution of the oxide of cobalt in spirit of salt
(muriatic acid, 29) and afterwards diluted till nearly
the whole of its colour disappears, forms one of the
most beautiful sympathetic inks with which we are acquainted.
If a landscape be drawn with Indian ink,
and, afterwards, the foliage be washed over with this
solution, it will have no peculiar appearance; but, on
holding the paper near the fire, the part representing
the vegetation will gradually assume a green tint,
which will subside on removing the paper into a cool
situation.
.sp 2
.fs 85%
248. MANGANESE, in the state that we usually see it,
is a black oxide of a metal which is of a silvery grey colour,
of leafy or foliated texture, and somewhat more than six times
as heavy as water.
.fs 100%
Mines of manganese have long been worked in several
parts of Great Britain, but particularly in the
counties of Devon and Somerset. Near Exeter and
in the Mendip Hills this mineral is found in great abundance.
It is employed for various useful purposes. In the
manufacture of the finer kinds of glass it is used in a
double capacity, both as a colouring material and as a
destroyer of colour. As a colouring ingredient, the
imitators of several precious stones are indebted to it
for the red and purple tints which they give to the
oriental ruby, the balais ruby, and the amethyst.
The violet colour given to porcelain is obtained from
manganese. This substance is also used for the glazing
of black earthen ware, as a paint, and an ingredient in
// 238.png
.pn +1
printers’ ink. As a discharger of colour it is applied in
small quantities, and, by the oxygen which it gives out,
it is said completely to destroy any tinge left in the glass,
by the presence of iron, and some other colouring matters.
This property has obtained for it the appellation
of the soap of glass.
It is from manganese that all the oxygen gas (#21:n21#)
used by chemists is obtained. By the application of a
red heat this is yielded in such abundance that an ounce
of the oxide of this metal will yield about two quarts of
gas. The consumption of manganese has, of late years,
become very considerable by the discovery of the
oxygenated muriatic acid, which is now extensively
used in the bleaching of linen and cotton; that liquor
being made by the distillation of the oxide of manganese
with spirit of salt (muriatic acid, 29).
// 239.png
.pn +1
.sp 2
.pb
.sp 4
.h3
COMPOUND MINERALS,
.sp 2
.nf c
OR
ROCKS.
.nf-
.hr 10%
.sp 2
249. There exist considerable masses of minerals in
a state of combination, or aggregation with each other.
These constitute the rocks and soil of which the globe
of the earth is composed; and the study of them is
called GEOLOGY. The opinions of learned men relative
to their structure, and original formation, have produced
various systems denominated theories of the earth;
but, when we consider that the greatest depth beneath
the surface to which the art and industry of man have
been able to penetrate, does not exceed 1/35000 part of
the earth’s diameter, we must confess that this is very
insufficient to allow of any correct opinion being
thereby formed concerning the structure of the whole.
Modern geologists, for the more convenient arrangement
of the compound minerals, have divided them
into four classes, which they denominate primitive rocks,
secondary rocks, alluvial depositions, and volcanic rocks.
.sp 2
.h4
I. PRIMITIVE ROCKS.
250. These are so called from their being considered by
geologists, to belong to the first formed parts of the globe.
Rocks of this description are of a nature extremely
hard. They contain no vestiges whatever of animal
or organic remains; and the substances of which they
are composed are crystallized. They rise through other
rocks at various elevations, in every quarter of the
globe; and never either alternate with, or rest upon
rocks that enclose organic remains, though they are
themselves frequently covered by such.
The following are the principal kinds.
// 240.png
.pn +1
251. GRANITE or moonstone is a compound rock
composed of felspar (#110:n110#), quartz (#76:n76#), and mica (#123:n123#), each
in crystalline grains of various size, and promiscuously arranged;
sometimes one and sometimes the other of these ingredients
predominates, but generally the felspar.
This is one of the most common and most widely extended
rocks that are known; and is considered as the
foundation on which the secondary rocks are deposited.
In Cornwall it is very abundant, and veins both of copper
and tin are found in it. Granite forms the summits of
the highest mountains in Scotland, of the highest of the
Grampian Hills, the Alps, and the Pyrenees; and indeed
the loftiest parts of most of the countries of the
world. The Logan or rocking stones, in Cornwall, are
immense blocks of granite.
The uses of this stone are numerous and important.
Millstones, steps, troughs for stamping mills, and innumerable
other articles, are made of it. The streets of
London are chiefly paved with granite, and its hardness
and durability render it peculiarly eligible for this use.
Weather has little effect upon it. Consequently, when
applied to architectural purposes it is found infinitely
preferable to Portland stone, of which nearly all the
public buildings of modern date in London have been
constructed, and many of which are fast going to decay.
This circumstance induced the proprietors of the
Waterloo Bridge to adopt granite in the construction
of that edifice. Mr. Smeaton also chose it for the
outer walls of the Eddystone Lighthouse.
252. Scottish Granite.—Scotland is remarkable
for many kinds of granite, some of which are susceptible
of an excellent polish. The greatest part of the
mountain of Ben Nevis, near Fort William, is composed
of a reddish granite, one of the best and most beautiful
that is known. This mountain is nearly a mile in perpendicular
height, and is said to contain granite enough
for all the kingdoms of the earth, although they should
be as partial to this stone as the ancient Egyptians
// 241.png
.pn +1
were. Columns and obelisks of any size and height
might be cut from it: for the rock is one uniform mass,
without appearance of strata, division, or fissure of any
kind. A convincing proof has been given of the strength
and hardness of this granite, in a fragment of several tons’
weight, which fell from nearly the top of a precipice
five hundred yards in height, upon a hard and solid rock
below, and yet continued entire.
253. Granite of Ingria.—A beautiful red granite
is found in some parts of Russia, remarkable on account
of the felspar (#110:n110#) that it contains, appearing in round
or oval pieces, from half an inch to two inches in diameter.
This granite, when polished, exhibits shining
spots of round or oval shape, which give to it somewhat
the appearance of being studded with precious stones.
The royal summer garden at Petersburg is decorated
with a superb colonnade of Ingrian granite. The columns
are sixty in number, and each of a single piece
twenty feet high, and three feet in diameter. Many of
the public buildings in Petersburg are of this granite.
An immense block of it thirty-two feet long, twenty-one
feet broad, and seventeen feet high, forms the pedestal
of the celebrated equestrian statue of Peter the
Great, in that city.
254. Graphic Granite.—A singular kind of granite
has been discovered in the island of Corsica, and
lately near Portsoy in the north of Scotland. The
ground of this granite is a whitish or reddish yellow
felspar, in which are embedded crystals of quartz each
from an inch to an inch and half long, and several lines
in diameter. The name of graphic granite was given
to it in consequence of an imaginary resemblance which
the sections of these crystals have to Hebrew, or Arabic,
and sometimes to musical characters.
255. GNEISS is a primitive rock, consisting, like granite,
of felspar (#110:n110#), quartz (#76:n76#), and mica (#123:n123#), but differing
from that rock in its structure, being slaty.
// 242.png
.pn +1
Mountains of gneiss are not so steep as those of
granite, and their summits are usually rounded. Ben
Lomond and others in Scotland, and mount Rosa in
Italy, are almost wholly of gneiss, as well as the
middle part of the Pyrenees. It is not an uncommon
rock, but in Britain is of less frequent occurrence than
granite.
Many valuable metallic ores are found in veins of
gneiss. This rock also sometimes contains crystals of
garnet (#70:n70#), and tourmaline (#69:n69#).
256. MICA SLATE, or MICACEOUS SCHISTUS,
is a primitive rock of slaty structure, consisting principally
of quartz (#76:n76#) and mica (#123:n123#).
Like gneiss, it is rich in ores. It often contains beds
of magnetic ironstone (#235:n235#), galena (#239:n239#), copper,
blende (#241:n241#), cinnabar (#228:n228#), and sometimes even
gold. It frequently has garnets, and sometimes tourmalines
(#69:n69#), interspersed in different parts of it.
Mica slate occurs in many parts of Scotland; the
mountain of Schehallien, and the rocky adjacent country,
are in a great degree composed of it.
257.