24 ORGANIC AGRICULTURAL CHEMISTRY 



left retains its original ammonia nature. On decomposition 

 with water it goes back to ammonia. 



NC - NCa + 4 H2O ^ 2 NH3 + Ca(0H)2 + CO2 



Calcium 

 cyanamide 



This decomposition takes place in steps which cannot be well 

 explained here. The exact character of the reaction, at least 

 the extent to which it is completed, probably varies under 

 different conditions in the soil. The nature of its action is 

 still subject to investigation, but there is no doubt that the 

 compound will eventually be one of the important forms of 

 nitrogen fertilizers. Its common commercial name is lime- 

 nitrogen. Its value and importance is largely in connection 

 with its commercial method of preparation. 



When carbon (coal) is heated in an electric furnace with lime, 

 CaO, the common substance calcium carbide is produced. 



CaO + 3 C -> CaC2 + CO 



Calcivim 

 carbide 



This calcium carbide with water yields the common illuminat- 

 ing gas acetylene. When, however, it is heated with atmospheric 

 nitrogen calcium cyanamide is formed. 



CaC2 + N2 -> NC- NCa + C 



Calcium Calcium 



carbide cyanamide 



The source of the nitrogen, therefore, is the atmosphere, and 

 we are converting atmospheric nitrogen into a plant fertilizer. 

 The utilization of atmospheric nitrogen for the manufacture of 

 agricultural nitrogen fertilizers is the great chemical problem 

 » in relation to agriculture which chemists have been investigating, 

 especially during the last quarter of a century, and this com- 

 pound, calcium cyanamide, is one of the three important re- 

 sults of this work. 



The more detailed study of this compound, including its prac- 

 tical application as a fertilizer, belongs to the study of soils and 

 fertilizers and not to our present study. 



