88 SOURCE AND ASSIMILATION OF NITROGEN. 



Whence, we may ask, comes this increase of nitro- 

 gen ? The nitrogen in the excrements cannot repro- 

 duce itself, and the earth cannot yield it. Plants, 

 and consequently animals, must, therefore, derive 

 their nitrogen from the atmosphere. 



It will in a subsequent part of this work be shown, 

 that the last products of the decay and putrefaction 

 of animal bodies present themselves in two different 

 forms. They are in the form of a combination of 

 hydrogen and nitrogen, — ammonia^ — in the tem- 

 perate and cold climates, and in that of a compound 

 containing oxygen, — nitric acid, — in the tropics 

 and hot climates. The formation of the latter is pre- 

 ceded by the production of the first. Ammonia is 

 the last product of the putrefaction of animal bodies ; 

 nitric acid is the product of the transformation of 

 ammonia. A generation of a thousand million men 

 is renewed every thirty years : thousands of millions 

 of animals cease to live, and are reproduced, in a 

 much shorter period. Where is the nitrogen which 

 they contained during life ? There is no question 

 which can be answered with more positive certainty. 

 All animal bodies during their decay yield the nitro- 

 gen which they contain to the atmosphere, in the 

 form of ammonia. Even in the bodies buried sixty 

 feet under ground in the churchyard of the Eglise 

 des Innocens, at Paris, all the nitrogen contained in 

 the adipocire was in the state of ammonia.* Ammo- 

 nia is the simplest of all compounds of nitrogen; 

 and hydrogen is the element for which nitrogen pos- 

 sesses the most powerful affinity. 



The nitrogen of putrefied animals is contained in 

 the atmosphere as ammonia, in the form of a gas 



* In 1786 - 7, when this churchyard was cleared out, it was discov- 

 ered that many of the bodies had been converted into a soapy white 

 substance. Fourcroy attempted to prove that the fatty body was an 

 ammoniacal soap, containing phosphate of Jime, that the fat was simi- 

 lar to spermaceti and to wax, hence he called it adipocire. Its melting 

 point was 126.5° F. 



For notice of the analysis and opinions of other chemists, see Ure's 

 Dictionary of Arts and ManufactureSy p. 14. 



