_Of Tin._
Tin is a metal of a slightly yellowish cast, though harder than lead,
very malleable, but of no great tenacity; so that wires cannot be made
of it. It easily extends under the hammer, and plates of it, called
_tinfoil_, are made only one thousandth part of an inch thick, and might
be made as thin again.
Tin has less specific gravity than any other metal. It melts long before
ignition, at 410 of Fahrenheit, and by the continuance of heat is slowly
converted into a white powder, which is the chief ingredient in _putty_,
used in polishing, &c. Like lead, it is brittle when heated little short
of fusion, and may be reduced into grains by agitation as it passes from
a fluid to a solid state.
The calx of tin resists fusion more than that of any other metal, which
makes it useful in making an opaque white enamel.
Tin loses its bright surface when exposed to the air, but is not
properly subject to rust; so that it is useful in protecting iron and
other metals from the effects of the atmosphere.
Concentrated vitriolic acid, assisted by heat, dissolves half its weight
of tin, and yields vitriolic acid air. With more water it yields
inflammable air. During the solution the phlogiston of the tin uniting
with the acid, forms sulphur, which makes it turbid. By long standing,
or the addition of water, the calx of tin is precipitated from the
solution. The nitrous acid dissolves tin very rapidly without heat, and
yields but little nitrous air. With marine acid this metal yields
inflammable air. With aqua regia it assumes the form of a gelatinous
substance used by dyers to heighten the colour of some red tinctures, so
as to produce a bright scarlet in dying wool.
A transparent liquor, which emits very copious fumes, called, from the
inventor, _the smoking liquor of Libavius_, is made by distilling equal
parts of amalgam of tin and mercury with corrosive sublimate, triturated
together. A colourless liquor comes over first, and then a thick white
fume, which condenses into the transparent liquor above mentioned. Mr.
Adet has shewn, that this liquor bears the same relation to the common
solution of tin, that corrosive sublimate does to calomel, and has given
an ingenious solution of many of its properties.
Tin detonates with nitre; and if the crystals made by the solution of
copper in the nitrous acid be inclosed in tinfoil, nitrous fumes will be
emitted, and the whole will become red hot. Also if five times its
weight of sulphur be added to melted tin, a black brittle compound,
which readily takes fire, will be formed.
Another combination of tin, sulphur, and mercury, makes a light yellow
substance called _aurum musivum_ used in painting.
Tin is the principal ingredient in the composition of _pewter_, the
other ingredients being lead, zinc, bismuth, and copper; each pewterer
having his peculiar receipt. It is also used in coating copper and iron
plates, and in silvering looking-glasses, besides being cast into a
variety of forms, when it is called _block tin_.
Tin is sometimes found native, but is generally mineralized with sulphur
and arsenic. The latter is thought to be always contained in tin, and to
be the cause of the crackling noise made by bending plates of it.
_Of the Semi-metals._
Bismuth is a semi-metal of a yellowish or reddish cast, but little
subject to change in the air; harder than lead, but easily broken, and
reducible to powder. When broken it exhibits large shining facets, in a
variety of positions. Thin pieces of it are considerably sonorous.
Bismuth melts at about 460 deg. of Fahrenheit. With more heat it ignites,
and burns with a slight blue flame, while a yellowish calx, called
_flowers of bismuth_, is produced. With more heat it becomes a greenish
glass. In a strong heat, and in close vessels, this metal sublimes.
Vitriolic acid, even concentrated and boiling, has but little effect
upon bismuth; but the nitrous acid acts upon it with the greatest
rapidity and violence, producing much nitrous air, mixed with
phlogisticated nitrous vapour. From the solution of bismuth in this
acid, a white substance, called _magistery of bismuth_, is precipitated
by the affusion of water. This has been used as a paint for the skin
but has been thought to injure it.
The marine acid does not readily act upon bismuth; but when
concentrated, it forms with it a saline combination, which does not
easily crystallize, but may be sublimed in the form of a soft fusible
salt, called _butter of bismuth_.
Bismuth unites with most metallic substances, and in general renders
them more fusible. When calcined with the imperfect metals, it unites
with them, and has the same effect as lead in cupellation.
Bismuth is used in the composition of pewter, in printers' types, and
other metallic mixtures.
This metal is sometimes found native, but more commonly mineralized with
sulphur.