NOTES : NITROGEN PROBLEM IN RELATION TO WAR 389 



Before reviewing the economic status of these different proc- 

 esses and their relation to our needs in the war, I wish to call 

 your attention to one other chemical process, namely, the con- 

 version of ammonia into nitric acid. If we are going to fix 

 nitrogen as ammonia by either of the first three processes, we 

 must convert it into nitric acid, and this is done by the following 

 very simple chemical reaction with the aid of platinum gauze 

 as catalyst: 



4NH3 + 5O2 - 4N0 + 6H2O. 



Ostwald, some twenty-five years ago, discovered that, when a 

 mixture of air and ammonia is passed, over platinum and certain 

 other catalyzers, there is an oxidation of the ammonia in large 

 measure to nitric oxide, which, when the gases are cooled and 

 brought into contact with oxygen and water, goes through the 

 two reactions that have already been described, and nitric acid 

 is produced. This process has been perfected so that it is now a 

 very valuable means for getting nitric acid from ammonia. 



Let me now review the situation as to the development of 

 these processes. The cyanamide process uses materials that are 

 nearly universally available: limestone, coke, and nitrogen from 

 the air. The limestone must be of good quality and free from 

 magnesia to work satisfactorily, but there are abundant deposits 

 all over the world of suitable limestone. It uses a moderate 

 quantity of power; this is used especially in the first stage of the 

 process, in the production of the calcium carbide. So, as a 

 result of these conditions — the small amount of power and the 

 availability of the materials — this process has been installed all 

 over the world — in all the countries of Europe, in Japan, and at 

 Niagara Falls, Canada. It is understood that since the beginning 

 of the war the Germans have greatly extended their cyanamide 

 plants, although they have probably been using the product 

 mainly for fertilizer purposes rather than for the manufacture 

 of explosives. At the present time, this is the only process on 

 this continent which has been developed commercially on any 

 considerable scale. 



The synthetic process, which had been pretty well developed 

 in Germany before the war, and which has undoubtedly been 



