Bismuth Thiophosphate

Bismuth Thiophosphate is formed by the action of phosphorus pentasulphide on bismuth trichloride. It is a reddish-brown or black substance which is readily fusible without apparent decomposition and can be crystallised from the melt. It is not readily soluble in the usual solvents. It is decomposed by dilute hydrochloric acid with evolution of hydrogen sulphide; it is first oxidised and then dissolved by nitric acid. It is not attacked by solutions of alkalies.

A very unstable substance, which maybe bismuth dithiophosphate, BiPS₂O₂, is obtained by the action of magnesium dithiophosphate upon a bismuth salt. It is, however, readily decomposed even in ice-cold water and in alcohol.