310 AMMONIA AND NITRIC ACID. 



ascribed to them, of wliicli nothing could be known, 

 because the things themselves were not known. 



As the advocates of this theory can say nothing about 

 the nature of the nitrogenous compounds present in the 

 ground, they want to make us beheve that nothing at all 

 is known about them. But no one, who has an acquaint- 

 ance with chemistry, has the smallest doubt or uncertainty 

 respecting the origin of nitrogen in the arable soil. It is 

 derived either from the air, whence it is conveyed to the 

 earth in rain or dew ; or from organic substances accu- 

 mulated from a series of generations of dead and decayed 

 plants, or else from animal remains contained in the earth, 

 or incorporated with it by man in the form of excrements. 

 Animal and human excrements, bodies of animals in the 

 earth, corpses in theu^ coffins, all vanish, with the ex- 

 ception of their incombustible matters, after a series of 

 years; the nitrogen of their constituents is converted 

 into gaseous ammonia, and is distributed in the surround- 

 ing soil. The remains of extmct animal Ufe which are 

 embedded, to an enormous extent, in sedimentary strata, 

 or which of themselves constitute whole masses of rock, 

 attest the extraordinary distribution of organic hfe in the 

 former ages of the earth ; and it is the nitrogenous con- 

 stituents of these animal bodies, passing over into am- 

 monia and nitric acid, which still play an important part 

 in the economy of the vegetable and animal world. 



If the smallest doubt could exist on this question, it is 

 completely removed by the investigations of Schmid and 

 Pierre (' Compt. rend.' t. xlix. pp. 711-715). 



Schmid examined (see Peters. 'Acad. Bull.' viii. 161) 

 several specimens of Eussian black-earth (tscherno-sem) 

 from the Government of Orel, and among them three 

 from the same field, marked by him as ' virgin soil,' 

 of which we may assume that it had never been subject 



