Rhodium Monosulphide, RhS

A product having an empirical composition corresponding to that required for rhodium monosulphide is produced:

1. When rhodium is heated to dull redness in sulphur vapour. Combination takes place with incandescence. When the reaction has subsided any excess of sulphur is removed by heating in a neutral gas such as carbon dioxide.
2. By raising to white heat a mixture of sulphur and ammonium chlor-rhodite; and,
3. By fusing finely divided rhodium with iron pyrites. Treatment with hydrochloric acid leaves black, crystalline scales of rhodium sulphide. The sulphide may also be produced in the wet way by passing hydrogen sulphide into a solution of sodium chlor-rhodite, washing, and drying at an elevated temperature in a neutral gas. Leidie, however, gives reasons for believing that the various products obtained by the above methods are not simple chemical entities, but mixtures of rhodium and its sesquisulphide.