Art. IX. — Notes on the soluhility of Gold-Silver Alloys 

 in Cyanide of Potassium SoliUlons. 



By DONALD CLARK, B.C.E. 



[Eead 8tli September, 1898.] 



Some experiments were undertaken with the assistance of 

 Messrs. Johnson and Osborne, students at the School, in order 

 to determine the solubility of gold and silver alloys in potassium 

 cyanide solutions. 



Since pure gold never occurs in nature, and I have never met 

 an alloy containing less than 60 per cent, of gold and 40 per 

 cent, of silver, a series of alloys containing from 60 to 95 per 

 cent, of gold was prepared for solution. 



Gold cornets, which contain only a trace of silver, were taken 

 and melted with the amount of pure silver required to make the 

 given alloy. These were then rolled out and annealed, and 

 strips were cut off and carefully weighed. The strips measured 

 1 inch in length and ^ of an inch in width, and since they 

 weighed about two grains, their thickness would be ^i^ of an 

 inch. 



Small bulbs were blown on glass tubes, and a pin hole made 

 in each bulb ; into one of these each metallic strip was inserted 

 and the whole were immersed in an inverted bell jar containing 

 a '25 per cent, solution of potassium cyanide, the liquid was 

 kept several inches above the gold and was allowed to slowly 

 drop through the stopper of the jar, thus ensuring a constant 

 and fresh supply of cyanide for the gold. It was intended to 

 have dissolved each of the strips completely, but it was found 

 that after 597 hours' contact that the gold had commenced to 

 separate out in fine flakes, and that several of the strips were 

 eaten through, so it was decided to assay the undissolved alloy 

 in order to find if its composition remained unaltered. The 

 temperature of the laboratory during the time of experiment 

 varied from 35°F. to 65°r. 



