NITRIFICATION 99 



bonate, or first may be changed to benzole acid and glyco- 

 coll. The latter is then ammonified. The ease with which 

 the ammonification of the nitrogenous bodies in urine takes 

 place accounts for their high availability as nitrogenous 

 fertilizers. 



Nitrification. AVliile some of the plants having eco- 

 nomic value can make use of ammonia, others can not, and 

 it is necessary to have the ammonia oxidi/nl to nitric acid. 

 This process can be accomplished by purely chemical 

 means. Many porous substances have the property of oc- 

 cluding gases or of condensing them. The modification of 

 plat iuum known as sponiry platinum has this property in a 

 high degree. If ammonia is brought in contact with spongy 

 platinum, it will be oxidized to nitric acid. 



Before anything was known of the activity of bacteria 

 in such processes, it was thought that the soil represented 

 such a porous medium. This view was strengthened by the 

 manner in which nitrates were made in earlier times. 

 Lai L:C amounts were needed for the gunpowder used in the 

 almost unceasing war operations. The natural deposits 

 then known were insufficient for these purposes, hence the 

 necessity of manufacturing nitrates arose. This was ac- 

 complished by mixing organic matter with earth. The mix- 

 ture was piled about brushwood, which served to make the 

 pile more porous. The pile was kept moist, and a neutral 

 reaction maintained by the addition of limestone to the 

 mixture of soil and organic matter. After a period the pile 

 was leached with water, and the nitrates that had in some 

 manner been formed were recovered. These piles were 

 known as saltpeter plantations. The calcium or sodium 

 nitrate thus obtained could be changed to potassium nitrate 

 by treatment with the lye leached from wood ashes. Un- 

 til the discovery of the great deposits of sodium nitrate in 

 Chile, the larger part of the nitrates used in the industries 



