Chromous Thiopyrophosphite, Cr₂P₂S₆

Chromous Thiopyrophosphite, Cr₂P₂S₆, called by Ferrand a thiohypophosphate, has been obtained by heating the metal with sulphur and red phosphorus as in the preparation of the preceding salt, the proportions of the elements being varied, and the heating continued for twenty-four hours. It crystallises in lustrous, black, hexagonal lamellae, which are insoluble in nitric acid and only slightly soluble in aqua regia.