The Cyanide of Potassium Process. 6g 



which is 23erhaps the best developed and generally 

 the most attractive of all the mines in the Randt. 

 The Ferreira Mine, adjoining the Robinson, is 

 justly celebrated for its splendid milling plant and 

 machinery, and for its economical and skilful 

 administration. The mine consists of about hfteen 

 claims, yielding, on an average, nearly one ounce 

 to the ton. The concentrates and tailings of this 

 mine, when properly treated, are expected to 

 produce a considerably additional yield. Here 

 has been installed a very perfect assav and smelt- 

 ing plant and laboratory. By the courtesy of the 

 very skilful gentleman in charge of this depart- 

 ment, Dr. Simon, I was enabled to follow the 

 beautiful process of the treatment of pyrites by 

 chlorine gas. The pyrites are roasted previously 

 to treatment, becoming extremely friable, losing 

 the suliDliur which they contain, freeing the gold, 

 and rendering it accessible to the attractions of 

 chlorine. In the McArthur-Forrest process, or 

 the cyanide of potassium process, the tailings do 

 not require to be roasted, the expense of treatment 

 being thereby considerably reduced, l3ut it is 

 asserted that the McArthur-Forrest j^rocess is only 

 available for the treatment of tailings "where the 

 gold is free, and that it produces no appreciable 

 results when treating pyritic concentrates.^ In 

 the simple chlorination process the pyrites having 

 been roasted (sufficiently to make them porous, 



^ This statement, Avliich was made on the authority of 

 Dr. Simon^ is altogetlier denied by the representatives of tlie 

 McArthur-Forrest process. 



