Salts of Auricyanic Acid

The free acid has not been prepared, as it decomposes as indicated under auric cyanide. Potassium auricyanide, 2KAu(CN)₄,3H₂O, is obtained in colourless crystals by the action of auric chloride on potassium cyanide in aqueous solution. It is readily soluble in water. At 200° C. all the water of crystallization is eliminated, the salt being converted into potassium aurocyanide, KAu(CN)₂. Ammonium auricyanide, NH₄Au(CN)₄,H₂O, is produced by evaporating a solution of auric hydroxide in ammonium cyanide. It forms large plates, readily soluble in water. At 100° C. the water of crystallization is expelled, and at higher temperatures the salt decomposes. The silver salt is produced as a yellowish precipitate, sensitive to light, by the action of silver nitrate on potassium auricyanide. It is readily soluble in ammonia, and much less readily in nitric acid. A cobaltous auricyanide, Co(Au(CN)₄)₂,9H₂O, and a number of complex salts have been prepared.