antimony - Sciencemadness.org

THE ANTIMONY PREPARATIONS AND THEIR USES. 165
has been found native in the lavas of Vesuvius. There exist many
processes for manufacturing it. According to Brunner, a German
chemist, it can be produced thus:—A mixture of 2 parts of tartar
emetic and 4 parts .of marine salt is calcined gently in a Hesse
crucible just to the point of fusion. After cooling, the mass is
crushed and then washed with water.
(fi) Messrs Hallet and J. Stenhouse in 1861 took out a patent in
England for manufacturing antimony yellow. This is produoed by
using *the oxides and the sulphides of antimony, with variable proportions
of antimony, oxide of iron, silica, water, and sometimes
arsenic, giving rise to various hues from a light yellow to a yellowish
red. The gangue is removed as far as possible by picking and
washing the ore, after which it is ground and sifted. The ground
mass is introduced into large crucibles, muffles, or reverberatory
furnaces, where it is carefully calcined at a dull red heat with access
of air. The mass is constantly stirred in order to prevent too high
an elevation of its temperature. During the operation, the powder
emits steam, sulphur, sulphurous acid, fumes of antimony and
arsenic, and becomes less fusible. The calcination lasts for from two
to three hours, and is completed when vapours and fumes are no longer
disengaged and when all the antimony has been transformed into
anhydrous antimonious acid. The impure antimonious acid is
reduced to an impalpable powder by grinding and levigation. After
drying, it forms with oil, varnish, etc., a pigment which may be combined
with oxides or salts, such as zinc oxide, white lead, chromate
of lead. The yellow pigment is obtained when the following constituents
are mixed together: 8 parts of native oxide of antimony, or
of the oxide mixed with the sulphide, or the impure antimonious
oxide obtained by the above-mentioned process; 3 parts of red lead or
litharge; and 1 part of oxide of zinc. This mixture is powdered and
calcined in crucibles, muffles, or furnaces, until combination is
effected and the final yellow colour has appeared. The mass is then
finally powdered and ground in oil or in varnish. By varying the
proportions, one can obtain various tones and hues of Naples yellow :—
Antiinonious acid
Oxide of lead
Oxide of zinc
In trade this pigment goes under various names, such as Naples
yellow, jaune, solid yellow, antimony yellow.
(y) The Process of Merome.—A mixture of 3 parts of finely
I.
i21
II.
1
2 1
III.
331
IV.
111
V.
11
VI.
21