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.
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 them, as a cathartic.
Realgar is poisonous, but by no means so much so as arsenic (242).
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 was not regularly worked till 1763. In the first five
years about a hundred tons’ weight of antimony were obtained from it.
This at 84_l._ per ton, produced the sum of 8400_l._ 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,[4]
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.
Footnote 4:
Ch. ix. v. 30. See also Ezek. Ch. xxiii. v. 40.
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._
_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), 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, 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. By so
doing, the upper portion, which is fluid, is made to run off, and a cake
studded with crystals will be left.
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._
_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)
with arsenic, or with sulphuric acid (21)._
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 15,000_l._ 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 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 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.
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._
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 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) 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).
────────────────────────────────────────────────────────────────────────
COMPOUND MINERALS,
OR
ROCKS.
───────
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_.
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.
251. _GRANITE or moonstone is a compound rock composed of felspar (110),
quartz (76), and mica (123), 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 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) 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.