NOTES : NITROGEN PROBLEM IN RELATION TO WAR 383 



obtained are lost. During the last decade, and especially during 

 the last few years, there has been a very rapid introduction of the 

 so-called "by-product" ovens, in which the coal is heated in 

 closed retorts and the gases are passed through condensers and 

 scrubbers by which the hydrocarbons and the ammonia are 

 recovered. It was alleged by some of those representing the by- 

 product industries that this supply of ammonia would alone 

 suffice to meet the military needs of the Government; but the 

 result has proved that it is utterly inadequate. Even if we pro- 

 duced all of our coke in by-product ovens, the supply would be 

 far from sufficient. Of course, the Government is interested in 

 extending the introduction of by-product ovens as rapidly as 

 possible; but the by-product industry is tied up with the steel 

 industry. It is mainly in the metallurgy of steel that coke finds 

 its use, and we can produce ammonia only in proportion as there 

 is a demand for coke. It is true that in Germany, where in the 

 early stages of the war the need for hydrocarbons was very 

 acute, coal was coked extensively just for its ammonia and hydro- 

 carbons, and great quantities of coke were piled up, to be used 

 after the war. Our Government has not yet felt that our needs 

 warrant such extreme action as this, as the value tied up in the 

 coke is large compared to the value of the by-products, and the 

 difficulties of securing deliveries are serious. 



Our third source of these nitrogen compounds is atmospheric 

 nitrogen. During the last fifteen years there have been de- 

 veloped a number of chemical processes by which the nitrogen 

 of the air is ''fixed," as we say, whereby ammonia, nitric acid, or 

 sodium cyanide are produced. I wish particularly to speak 

 of the four most important processes which have been operated 

 on a commercial scale. These are the cyanamide process, the 

 cyanide process, the arc process, and the synthetic process. 



Let me briefly describe to you the principles involved in these 

 different chemical processes. I shall endeavor to show you 

 what materials are needed and how far power enters as a factor. 



1. In the cyanamide -process we start with lime and powdered 

 coke. The first chemical reaction that takes place results in the 

 formation of calcium carbide, as follows: 



CaO + 3C = CaCa + CO. 



