The Patio and Cazo Process. 2? 



of copper act, the one on the other, and give rise to chloride 

 of copper and sulphate of soda :* 



CuS0 4 + 2 Na 01 = Cu 01, + NaJ30 4 . 



The chloride of copper acts on the metallic silver and the 

 sulphide of silver ; chlorides of silver are formed, which are dis- 

 solved in the excess of chloride of sodium. 



2 Ag + 2 Cu 01, = 2 Ag CI + Cu, 01 2 . 

 Ag, S + Cu 01, = 2 Ag CI + Cu S. 



When mercury acts on artificially prepared chloride of silver, 

 it reduces it to a metallic state, when it enters into combination 

 with the mercury. 



2 Ag 01 + I Hg = Hg 01, + Ag, Hg. 



This reaction takes some time, and is less sensible on the 

 natural than on the artificial substance. 



If chloride of copper is treated with mercury, sub-chloride of 

 copper and sub-chloride of mercury are formed. 



2 Cu C! 2 + 2 Hg = Cu, 01, + Hg, Cl 2 . 



This reaction takes place more rapidly than with chloride of 

 silver. If chloride of iron is substituted for the chloride of 

 copper, all the reactions take place, but much more slowly, and 

 this is especially true when sulphide of silver is present. The 

 presence of salt accelerates the reactions in all cases. If any of 

 the metallic silver in the ore has not been transformed into 

 chloride, this is attacked directly by the mercury. 



When sulphide of silver and mercury are shaken together, 

 sulphide of mercury and amalgam are formed. 



Ag, S + 2 Hg = Ag, Hg + Hg S. 



This reaction is slow but much quicker than with chloride of 

 silver. All the sulphide of mercury is entirely lost. 



Rammelsberg and Huntington have recently made the fol- 

 lowing investigations :f If sulphide of silver and chloride of 

 copper are made to act on each other, either sub-chloride of cop- 



* Berg und Hiittenmannisclie Zeitung, 1881, p. 303. 



f Die Metallurgie des Silbers und Goldes, von J. Perc}', p. 12, Bruns- 

 wick, 1881, and Min. Eng. Journal, Vol. 34, p. 150. 



