Antimonii Sulphuratum. U.S., Br. - Antimonii Sulphuretum Praecipitatum. U.S. 1850. - Precipitated Sulphuret of Antimony.

This is prepared by boiling together powdered sulphuret of antimony and solution of potassa or soda; then filtering, and precipitating with sulphuric acid, while the solution is still hot; and lastly washing the precipitate. A double decomposition takes place between the sulphuret of antimony and potassa (oxide of potassium), by which the oxide of antimony and sulphuret of potassium are formed; a portion of the sulphuret of antimony and of the alkali remaining undecomposed. The oxide of antimony formed, and a portion of the residuary sulphuret of antimony, though insoluble in pure water, are held in solution, the former through the instrumentality of the remaining alkali, and the latter by the sulphuret of potassium produced. The sulphuric acid, by neutralizing the potassa or soda used, and decomposing the sulphuret of potassium,. does away with the solvent property of the liquid; and the oxide and sulphuret of antimony consequently fall, being combined together as an oxysulphuret.

Properties

Precipitated sulphuret of antimony is an orange or reddish-brown powder, without smell, tasteless if quite pure, but usually somewhat styptic, and insoluble in water. When heated, it burns; sulphurous acid escaping, and a grayish oxide of the metal being left. Most of the preparation is dissolved by muriatic acid, with the escape of sulphuretted hydrogen; and, if the resulting solution be poured into water, a white precipitate is produced, which is the powder of Algaroth, and chemically an oxychloride of antimony. According to Mr. Phillips, the precipitated sulphuret contains, in 100 parts, 16.5 of sulphuret of antimony, 12 of oxide of antimony, and 11.5 of water.