A N T I M O N Y : ITS HISTORY, CHEMISTRY, MINERALOGY ...

THE ANTIMONY PREPARATIONS AND THEIR USES. 157
dried at 100°. Again, a mixture of bauxite and antimonic acid may
first be treated with steam, and then calcined slowly under a current
of carbonic acid gas. Finally, the antimoniates of manganese and of
zinc give a good white colour.
(b) Antimony Black.—It is obtained by treating antimony
solutions with zinc or iron. The deposit thus obtained is in the form
of powder, and ia used to bronze metals or plaster.
(c) Antimony Vermilion.—Lampadius, in 1853, proposed using
the red sulphide of antimony as a pigment, which, as he observed,
covers well when employed with water, but possesses less body when
ground with oil.
M. E. MathieurPlessy writes thus* :—"The product to which I
give the name vermilion of antimony is the result of a new modification
of the sulphide of antimony which I obtain from the decomposition
of hyposulphite of soda in the presence of chloride of
antimony.
"Among the phenomena of double decomposition, so characteristic
of the nature of mineral substances, none is more striking than the
production of the orange-yellow sulphide of antimony by means of
sulphuretted hydrogen or of an alkaline sulphide. If the latter
reagent, from long exposure to the air, be partly transformed into
hyposulphite, it may give with a proto-salt of antimony variously
coloured precipitates, the colour depending on the degree of oxidation.
These variations, which may have been already observed, will
be easily explained by the reaction studied by myself, which gave the
key for obtaining a red sulphide of antimony entirely distinct from
the well-known ones hereafter mentioned.
" I refer to the orange-yellow sulphide, produced by the reaction of
sulphuretted hydrogen upon the proto-chloride of antimony, the
black native sulphide, and the brown-red sulphide, a modification of
the preceding one, which was observed for the first time by Fuchs,
and has recently been studied by Mr Rose.
" It is not sufficient, however, to put the proto-chloride of antimony
and the hyposulphide of soda in contact with each other to obtain
the sulphide of antimony with all the brightness which it is able to
acquire. In order always to arrive at the desired result, I have been
obliged to make numerous trials and to vary the proportions of the
reagents and the temperature. At last I have succeeded in finding
out a process which is satisfactory in regard to the quality of the
product and the facility of its preparation.
" Believing that the vermilion of antimony might find its applica-
* Bull, de la Soc/UU industrielle de Mulhousc, vol. xxvi. pp. 297 et seq.