2 CYANAMID — MANUFACTURE:, CHEMISTRY AND USES 



ttire of barium carbide, sodium hydroxide, potassium hydroxide 

 and carbon at a high temperature to the action of steam and 

 nitrogen. Frank and Caro, with the co-operation of F. Rothe, 

 found in 1895 that dry nitrogen is essential to successful 

 absorption. 



In 1898 it was found that when barium carbide is heated to 

 a temperature of 7CX)° to 800° C, in the presence of nitrogen, 

 about 30 per cent, of the carbide is changed into barium 

 cyanide and the remainder into barium cyanamide. The re- 

 actions can be represented by the following simple equations: 

 BaC, -f N, = Ba (CN)„ 

 Ba(CN), = BaCN^ + C. 

 Since it was desired to have all the nitrogen in the form of 

 cyanide, further operations were necessary. The product of 

 the above reactions was fused with soda, when the carbon 

 again reacted with the cyanamide group and produced the 

 cyanide form. The cyanide was leached out with water, and 

 treated with ferrous carbonate to form the f errocyanide, which 

 was sold as such or fused with sodium to form pure sodium 

 cyanide. The barium carbonate residue was again used to 

 produce barium carbide, as represented by the reactions : 

 BaCOj -f heat = BaO -f CO^, 

 BaO + 3C = BaC, + CO. 



The fall in the price of cyanides due to the interruption in 

 the production of gold during the Boer War in South Africa 

 made it necessary to seek cheaper methods of manufacture. 

 It was found that calcium carbide could be manufactured at 

 less cost, and also had the advantage of possessing a lower 

 molecular weight. This carbide required a temperature of 

 from 1,100° to 1,200° C. for the absorption of the nitrogen, but 

 combined it entirely in the form of calcium cyanamide, without 

 the formation of any cyanide. By fusion with alkaline salts, 

 however, the cyanamide form, in the presence of carbon, 

 readily goes over to the cyanide form, which can be leached 

 out with water, if desired, and be further purified. When 

 sodium chloride is used as the fluxing agent, the resultant mass 



