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

182
THE METALLURGY OF ANTIMONY.
volatilised antimony can more than counterbalance the impurities
that may be present.
2. Wet Methods.—(a) Gravimetric.—(a) Determination as Trimlphide,
SB.,S3.—H2Sis passed for twenty minutes into the cold solution
of an antimonite or antimonate. The solution is then heated to
'Asbestos
FIG. 63.
Filter plate
boiling, the current of H2S being still maintained up to fifteen minutes
after the commencement of boiling. Tbe dense precipitate is then
filtered through a Gooch crucible."* It is then washed with 50 to 75
per cent, of very dilute and hot acetic acid into which H2S has been
passed, dried, and heated in a Paul's drying-oven to 230° for not
Therrfi.
FIG. 64.
/-•• Watch • glass
more than half an hour. The sulphur volatilised from the precipitate
is collected in watch-glasses. As soon as all the sulphur has
been driven off, the crucible* is allowed to cool and is weighed.
(£> Determiruition as Tetroxide, Sb2O4, according to Rbssing.—The
sulphide of antimony, precipitated from a hot solution, is washed
(1) with hot water, (2) with alcohol, (3) with a mixture of alcohol
* For & short description of this crucible, vide pp. 24-25, Hall's Analytical
Chemistry, vol. ii; ; N.Y., Wiley, & Sons, 1905.