Ammonia Processes in Manures 321 



found in the nitrate that is formed in the course of time 

 in the surface layers. It happens, at times, that the 

 nitrate thus formed is diffused downward and is reduced 

 there to nitrite and to ammonia. 



Hippuric acid. — The liquid excreta of herbivorous 

 animals contain their nitrogen for the most part in a 

 substance called hippuric acid which is derived from 

 the protein substances in the food. Hippuric acid is 

 readily decomposed with the formation of a simpler 

 substance, glycocoll, which, in turn, is changed by bac- 

 teria into carbonate of ammonia. 



Uric acid. — In a similar manner, the nitrogenous 

 substances in the liquid excreta of carnivorous animals 

 consist largely of urea and uric acid. These also are 

 changed by bacteria into carbonate of ammonia. The 

 ammoniacal odors in stables are due to this formation 

 of carbonate of ammonia from liquid manure. The 

 carbonate is a substance that is readily vaporized at 

 ordinary temperatures and is used for this reason, in 

 the preparation of smelling salts. 



The formation of ammonia in liquid excreta. — -The 

 conversion of the nitrogenous substances in liquid 

 excreta into carbonate of ammonia proceeds very rapidly. 

 Wagner observed that a quantity of cow urine containing 

 thirty-nine parts of nitrogen included only one part of 

 ammonia nitrogen in a fresh condition. At the end of 

 two days, there were twenty-three parts of ammonia 

 nitrogen in the liquid and at the end of four days, thirty- 

 five parts. Thus in four days all but four parts of the 

 initial nitrogen had been converted into ammonia. 

 He observed, also, that when the urine was mixed with 



