Auric chromate

Auric Chromate.—For an account of the preparation and properties of auric chromate reference should be made to this series, Vol. VII. 

Gold Chromates. —A red solution of auric chromate, Au2(CrO.,).j, is obtained treating a solution of auric chloride with a large excess of freshly precipitated silver chromate. On evaporation, first metallic gold is precipitated, and then the compound Au2(Cr04)3.Cr0g crystallises out. 

It is precipitated by potassium chromate, ferricyanide, bismuthi-iodide, and mercuri-iodide, ammonium molybdate, platinic chloride, and auric chloride [1]. 

N. A. OrlofE 1 prepared an orange-coloured soln. of gold Chromate, Au2(Cr04)3, by adding a soln. of auric chloride to an excess of freshly precipitated silver chromate, and filtering ofi the silver chloride. If the cone. soln. be evaporated in a desiccator, crystals with the composition Au2(Cr04)3.Cr03 are formed. 

White precipitates are formed when a 1% solution of cusparine is treated with phosphotungstic, phosphomolybdic or tannic acids, or with mercuric chloride or potassium mercuri-iodide. Picric acid, platinic chloride or potassium chromate give yellow precipitates, auric chloride or potassium bismuth iodide brown, and potassium ferrocyanide bluish-white (36). By treating a solution of cusparine hydrobromide with bromine water, a series of bromocusparine polybromides is obtiuned(38). 

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