CYANAMID — MANUFACTURE, CHEMISTRY AND USES 9 



Dicyandiamide. — This derivative is easily prepared by leach- 

 ing the crude calcium cyanamide mass with hot water, pre- 

 cipitating the lime in the filtrate with carbon dioxide, and con- 

 centrating the filtrate. Dicyandiamide is used in the dye in- 

 dustry, and also as a deterrent in nitro-explosives, in place of 

 ammonium oxalate. 



Other derivatives, such as urea, guanidine, nitro-guanidine, 

 are being made at the Spandau works, in Germany. A process 

 has also been worked out for the production of synthetic indigo 

 by the action of dialkylcyanamides on Phenylgycine and its 

 derivatives. 



Ferrodur and intensit are special mixtures prepared for 

 metallurgical purposes. Ferrodur is a cementing powder used 

 in place of potassium cyanide for hardening iron and steel in 

 ovens. Intensit is a hardening powder for hardening iron and 

 steel in open fires; it is used in place of potassium ferro- 

 cyanide. There are other powders of a similar nature with 

 special names differing only in the proportion of active in- 

 gredients that they contain. These products are of consider- 

 able importance to metallurgy, since they are cheap, yet 

 efficient for the purposes for which they are sold. 



