184 ELECTROLYSIS. 



His method is based on the use of mixtures of zinc chloride 

 with alkaline chlorides, potassic, sodic, ammonic ; of zinc 

 acetates, with the corresponding alkaline acetates. 



For brass baths, use copper with the same acids as the salts 

 of zinc, acetates for example. 



For bronze baths, dissolve the double tartrate of protoxide 

 of tin and potassium, with or without addition of caustic 

 potash. 



Mr. Newton deposits an alloy of zinc, tin, and copper by 

 means of a bath composed of double cyanide of copper and 

 potassium, potassic zincate, and stannate ; he obtains these 

 latter by melting tin oxide with caustic potash, or by dissolving 

 in potash. 



For brass baths he uses a solution composed of cupric oxide 

 dissolved in an excess of potassic cyanide, zinc oxide, a small 

 addition of liquid ammonia, and heats to about 50 C. The 

 solution is completed with water, so that the liquid contains 2 

 of zinc for 1 of copper. 



Other Baths. 



Potassic cyanide 373 grammes. 



Ammonic carbonate 373 ,, 



Cupric cyanide 62 



Zinc cyanide 31 



Dissolve in 4 * 50 litres of water. Eaise the temperature to 

 65 C. 



Potassic cyanide I Equal weights. 



Ammonic carbonate j 



Dissolve in 4 * 50 litres of water. Attach a large brass anode 

 to the positive conductor of the battery, and use a small surface 

 of cathode, a thin sheet of brass for example. The temperature 

 must be about 65 C. The anode is dissolved, and furnishes the 

 metal required for the bath. 



DEPOSITION OF PLATINUM. 



KOSELEUK'S PROCESS. M. Koseleur was the first to succeed 

 in obtaining good platinum deposits. His patent is dated 

 1847. 



