The Patio and Cazo Process. 29 



chloride of copper, chloride of copper, sulphide of copper, and 



metallic silver are produced. 



Na CI, 0n a Cl 9 + Ag, 8 = Na 01, Ou Cl 3 + 0u S + 2 Ag. 



It thus appears, that while it cannot affect the chloride of silver, 

 the sub-chloride of copper can reduce sulphide of silver, which, 

 in the presence of mercury, is amalgamated without having 

 passed into the state of chloride at all. If ammonia is added to 

 the solution of the sub chloride of copper and chloride of sil- 

 ver, silver is precipitated. 



2 Ag CI + 0u 2 CI, + N H 3 = 2 Ag + 2 Ou Cl 2 + N H,. 



When chloride of silver, sulphide of copper, and ammonia are 

 heated, a blue solution is obtained. One half the chloride of sil- 

 ver is converted into sulphide of silver. The residue, which is 

 black, is composed of sulphide and chloride of silver, and con- 

 tains no copper. 



8 Ag 01 + 2 Cu S = Ag 01 + 2 Ag, 8 + 3 Ag 01 + 2 Ou CI,. 



Xot Dissolved. Dissolved. 



Three parts of chloride of silver and two of chloride of copper 

 remain in solution. 



If two parts of chloride of silver dissolved in ammonia are 

 treated with sub-sulphide of copper, a mixture of silver and sul- 

 phide of copper is precipitated, about one tenth of the silver 

 still remaining in solution. 



2 Ag CI + 0u a S = 2 Ag + Ou S + Ou CI,. 



If four parts of chloride of silver are used, the copper remains 

 almost entirely in solution, and 28.2 parts of the silver are also 

 in solution. The residue consists of metallic silver and sulphide 

 of silver. 



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



Prof. Huntington found, that when chloride of silver and sul- 

 phide of copper are mixed in an ammoniacal solution, sub- 

 chloride of copper is formed, which reacting on the chloride of 

 silver forms metallic silver and chloride of copper. 



2 Ag CI + Cu, S + x\ T H 3 = Ag, 8 + Cu, CI, X H,. 

 2 Ag 01 + Cu, CI, NB 3 = 2 Ag + 2 Cu CI, N H,. 



