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LXXVI. Account of a new Cyanide of Gold. 

 By Mr. John Carty*. 

 'TWERE is one compound of cyanogen and gold known at 

 x present to chemists ; it is a tercyanide, or contains 3 equi- 

 valents of cyanogen combined with one of gold. Having ob- 

 served indications of a protocyanide, and not rinding it men- 

 tioned in the chemical works usually referred to, I tried to 

 obtain it pure, and have, I believe, succeeded by the following 

 method : — 



Protochloride of gold was decomposed by cyanide of po- 

 tassium in solution. An abundance of a yellow matter ap- 

 peared at first, but an excess of the cyanide gave a clear and 

 perfect solution. To this solution muriatic acid in excess was 

 added ; on boiling a bright yellow powder precipitated, which 

 was washed and dried by a moderate heat. It was insoluble 

 in water, alcohol and aether; soluble in ammonia and in solu- 

 tion of cyanide of potassium. It was decomposed by heat, 

 like a cyanide, and nothing but cyanogen gas was driven off. 

 It was not decomposed by strong boiling muriatic or nitric 

 acid, or by a solution of chlorine, but was decomposed, though 

 not rapidly, by hot nitro-muriatic acid, and very slowly by so- 

 lution of potash ; boiling sulphuric acid liberated metallic gold. 



30'7 grains of the yellow powder were heated to redness in 

 the air, 27*0 of gold remained, 3*7 of cyanogen were therefore 

 driven off. Other experiments on smaller quantities agreed 

 closely with this, and they show the yellow substance to have 

 been composed as near as may be of 200 of gold and 26 of 

 cyanogen ; and it is therefore a protocyanide of gold. 



When tercyanide of gold was dissolved in boiling muriatic 

 acid, and the solution concentrated, protocyanide of gold was 

 gradually deposited as a yellow powder. 2 atoms of cyanogen 

 were removed, probably by forming ammoniacal compounds 

 with the elements of the water which is present. 



The protocyanide of gold was dissolved in hot ammonia; 

 on cooling an abundance of gray glistening plates fell, which 

 were found to be a compound of the protocyanide and am- 

 monia. The ammonia was easily removed by a gentle heat, 

 or by hot muriatic acid leaving the protocyanide. 



Protocyanide of gold was dissolved in solution of cyanide 

 of potassium. By evaporating the liquid, long prismatic 

 white crystals, nearly opake, anhydrous and somewhat de- 

 liquescent, were obtained. They were decomposed by heat 

 into gold, cyanogen gas and cyanide of potassium. A solu- 

 tion of them was not soon affected «by muriatic acid in the cold, 



* Communicated by the Chemical Society; having been read February 

 19, 1844. 



2 L 2 



