124 THE NEW WORLD OF SCIENCE 



This was, however, a precarious source of supply. For in 

 the first place, it required ships for its transportation, and ships 

 were scarce. In the second place, there was always danger 

 that enemy machinations, through the purchase of the Chilean 

 mines, destroying the plants, or blowing up the oil supply used 

 for fuel, would reduce the production; or that our supply 

 might be cut off entirely, by the establishment of a hostile sub- 

 marine base on the Pacific Coast. All of these possibilities 

 made it unsafe to rely for our nitric acid supply on Chile salt- 

 peter alone. But, even if none of them actually came about, 

 it would still be impracticable to get in this way the huge 

 amount of nitric acid that would be needed by the American 

 Army. 



The second source of nitrogen products is the ammonia 

 produced as a by-product in the manufacture of gas and coke. 

 There has been developed, as will be described later, a process 

 for the conversion of ammonia into nitric acid, so that if we 

 could get, from any source, an adequate supply of ammonia, 

 it could be converted into nitric acid. But unfortunately, this 

 country was still producing most of its coke in the so-called 

 " beehive " oven, which is simply a hemispherical kiln, into 

 which the coal is charged and set on fire ; the products of the 

 combustion being allowed to pass into the air, whereby the am- 

 monia and valuable hydrocarbons that might be obtained are 

 lost. It is true that during the preceding decade there had 

 been a 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 hydro- 

 carbons and the ammonia are recovered. It was even claimed 

 before the war by representatives of the by-product industry 

 that this rapidly increasing supply of ammonia would alone 

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

 result proved that it was utterly inadequate. The production 

 by this process is necessarily limited by the fact that the by- 

 product industry is dependent upon the steel industry; for it 

 is mainly in the metallurgy of steel that coke finds its use, 



