298 PHYSIOLOGY AT THE FARM. 



with. The name azote is derived from Greek words signify- 

 ing privation of life ; that is, nitrogen, though abundant in the 

 atmosphere, is not the element which supports life. It serves 

 merely to dilute the oxygen, which, when pure, so powerfully 

 stimulates that it at length extinguishes life. Neither does 

 nitrogen support combustion. Nitrogen is a most important 

 constituent of the organic structure, inasmuch as no organic 

 products destitute of nitrogen can augment or repair the 

 animal frame. Aliments destitute of nitrogen, usually called 

 non-azotised, are fit to support animal heat and to accumulate 

 fat, but not to nourish the solid frame of a living animal. The 

 nitrogen of the atmosphere, which constitutes nearly four-fifths 

 of its weight, does not directly act as nourishment to either 

 vegetable or animal bodies. The nitrogen of organic nature is 

 chiefly derived from the ammonia of the atmosphere, which 

 is constantly present, though in small quantity. Nitrogen 

 forms nearly five-sixths of ammoniacal gas. A question has 

 arisen whether the generation of ammoniacal gas can go on 

 without limit in nature. If this question were answered in 

 the negative namely, that ammoniacal gas cannot arise 

 except from the decomposition of organic tissues containing 

 nitrogen then there would be a limit to the increase of organic 

 nature ; thus, that it could not increase beyond what the 

 ammonia actually in the atmosphere and that derived from 

 the decomposition of the azotised organic products in actual 

 existence at present could afford, unless, indeed, a continued 

 supply could be counted on from volcanic sources. It seems, 

 however, certain that ammonia is actually formed on many 

 occasions in nature altogether independently of the decomposi- 

 tion of organic matter, or of the presence of volcanic influence. 

 When oxidation takes place in the presence of moisture, it is 

 attended with the formation of ammonia. Thus moistened 

 iron filings, if exposed to the air, become rusty, and the oxidised 



