_Of Antimony._
The regulus of antimony is of a silvery white colour, of a scaly
texture, very brittle, and melts soon after ignition. By continuance of
heat it calcines in white fumes, called _argentine flowers of antimony_,
which melt into a hyacinthine glass. In close vessels it rises without
decomposition. Its calx is soluble in water, like that of arsenic. This
metal tarnishes, but does not properly rust, by exposure to the air.
This metal is soluble in aqua regia. It detonates with nitre, and what
remains of equal parts of nitre and regulus of antimony after
detonation, in a hot crucible, is called _diaphoretic antimony_. The
water used in this preparation contains a portion of the calx suspended
by the alkali, and being precipitated by an acid, is called _ceruse of
antimony_.
When regulus of antimony is pulverized and mixed with twice its weight
of corrosive sublimate (which is attended with heat) and then distilled
with a gentle fire, a thick fluid comes over, which is congealed in the
receiver, or in the neck of the retort, and is called _butter of
antimony_. The residuum consists of revived mercury, with some regulus
and calx of antimony. When this butter of antimony is thrown into pure
water, there is a white precipitate, called _powder of algaroth_, a
violent emetic. Nitrous acid dissolves the butter of antimony; and when
an equal weight of nitrous acid has been three times distilled to
dryness from butter of antimony, the residuum, after ignition, is called
_bezoar mineral_, and seems to be little more than a calx of the metal.
Crude antimony, which has been much used in the experiments of
alchemists, is a combination of sulphur and regulus of antimony. Heat
melts it, and finally converts it into glass, of a dark red colour,
called _liver of antimony_. If antimony be melted or boiled with a fixed
alkali, a precipitate is made by cooling, called _kermes mineral_,
formerly used in medicine. The antimonial preparations that are now most
in use are _antimonial wine_ and _tartar emetic_. The wine is made by
infusing pulverized glass of antimony in Spanish wine some days, and
filtering the clear fluid through paper. The emetic tartar, or
antimonial tartar, is a saline substance, composed of acid of tartar,
vegetable alkali, and antimony partially calcined. The preparation may
be seen in the Dispensaries.
The regulus of antimony is used in the form of pills, which purge more
or less in proportion to the acid they meet with; and as they undergo
little or no change in passing through the body, they are called
_perpetual pills_.
_Of Manganese._
Manganese is a hard, black mineral, very ponderous, and the regulus of
it is a semi-metal of a dull white colour when broken, but soon grows
dark by exposure to the air. It is hard and brittle, though not
pulverizable, rough in its fracture, and of very difficult fusion. Its
calces are white when imperfect, but black, or dark green, when perfect.
The white calx is soluble in acids. When broken in pieces, it falls into
powder by a spontaneous calcination, and this powder is magnetical,
though the mass was not possessed of that property. The black calx of
manganese is altogether insoluble in acids. It contains much
dephlogisticated air.
The calx of manganese is used in making glass; the glass destroying the
colour of that of the other materials, and thereby making the whole mass
transparent.
This semi-metal mixes with most of the metals in fusion, but not with
mercury.
There is another ore of manganese, called _black woad_, which inflames
spontaneously when mixed with oil.
_Of Wolfram._
Wolfram is a mineral of a brownish or black colour, found in the tin
mines of Cornwall, of a radiated or foliated texture, shining almost
like a metal. It contains much of the calx of manganese, and iron; but
when the substance is pulverized, these are easily dissolved, and the
calx of wolfram is found to be yellow.
This calx turns blue by exposure to light; and an hundred grains of it
heated with charcoal will yield sixty grains of a peculiar metal, in
small particles, which, when broken, look like steel. It is soluble in
the vitriolic or marine acids, and reduced to a yellow calx by nitrous
acid or aqua regia.
_Of Molybdena._
Molybdena is a substance which much resembles plumbago; but its texture
is scaly, and not easily pulverized, on account of a degree of
flexibility which its laminae possess. With extreme heat, and mixed with
charcoal, it yields small particles of a metal that is grey, brittle,
and extremely infusible; and uniting with several of the metals, it
forms with them brittle or friable compounds. By heat it is converted
into a white calx.
_Of Solid Combustible Substances._
There yet remains a class of solid substances, of the _combustible_
kind, but most of them have been already considered under the form of
the fluids, from which they are originally formed, as _bitumen_,
_pit-coal_, and _amber_; or under the principal ingredients of which
they are composed, as _sulphur_ and _plumbago_.
There only remains to be mentioned the _diamond_, which is of a nature
quite different from that of the other precious stones, the principal
ingredient in which is siliceous earth, which renders them not liable to
be much affected by heat. On the contrary, the diamond is a combustible
substance; for in a degree of heat somewhat greater than that which will
melt silver, it burns with a slight flame, diminishes common air, and
leaves a soot behind. Also, if diamond powder be triturated with
vitriolic acid, it turns it black, which is another proof of its
containing phlogiston.
The diamond is valued on account of its extreme hardness, the exquisite
polish it is capable of, and its extraordinary refractive power; for
light falling on its interior surface with an angle of incidence greater
than 24-1/2 will be wholly reflected, whereas in glass it requires an angle
of 41 degrees.