46 PRINCIPLES OF AGRICULTURAL CHEMISTRY 



Argon, which is found in the air, is a gas related to nitrogen 

 and is apparently incapable of entering into chemical combination. 

 It has no agricultural importance. Associated with argon in the 

 air, in very small quantity, are the other gases of similar char- 

 acter, namely, neon, helium, krypton, and zenon. 



A TMO 5PHE7VC NITROGEN 



Fig. 9. Circulation of nitrogen. 



Ammonia. The air contains about one part of ammonia in 

 fifty million. The column of air resting on an acre weighs about 

 41,300 tons, which would contain about 1.5 pounds ammonia. 

 Country air contains less ammonia than town air. The ammonia 

 in the air probably comes from the decay of organic nitrogenous 

 bodies, especially urine. The exhalations of volcanoes and 



