Cyanoplatinous Acid, H₂Pt(CN)₄

Cyanoplatinous Acid, H₂Pt(CN)₄, maybe prepared by decomposition of its mercuric or cupric salt suspended in water by a current of hydrogen sulphide. On filtration and evaporation bluish black prisms are obtained, which deliquesce on exposure to moist air. The salt is easily soluble in water, alcohol and ether. At 100° C. it decomposes into platinous cyanide and hydrogen cyanide. Sulphuric acid converts it into platinous cyanide. The aqueous solution reacts strongly acid, decomposes carbonates, and has an acid taste. The alcoholic solution deposits a mirror of platinum on the containing vessel when heated.