396 CHEMICAL DISCOVERY AND INVENTION 



saving is practically insignificant. The rest, with the phosphates, 

 is discharged into the sea. 



In all pasture land a certain amount of fixation of atmospheric 

 nitrogen is always going on through the agency of bacteria. 

 And it is fortunate that this is so, for without the secret, obscure 

 operations of such tiny things as the azotobacter, dostridium, and 

 a few other organisms, the necessary stimulant would be missing 

 from large parts of the earth's surface. The albuminous matters 

 thus stored up in the clovers and other leguminous plants yield 

 up their nitrogen again by decay, ammonia passing into the soil 

 and becoming the food of another generation. Here it may 

 perhaps be as well to warn the reader against confusing the 

 action of the bacteria which bring atmospheric nitrogen into 

 chemical combination producing protein substances in the plant, 

 with the action of those other properly called nitrifying organisms 

 by which ammonia is converted first by one microbe into nitrite, 

 and then by another into nitrate. These operations are of great 

 physiological irnportance as bringing the nitrogen into an 

 assimilable condition, but they add nothing to the soil. The 

 .farmer then must look for cheap nitrogen in the form of am- 

 monium sulphate or a nitrate to the chemist, in accordance with 

 the indication of Sir William Crookes in 1898. The supply has 

 begun, but at present the synthetical nitrogenous manures play 

 no great part in agriculture. Their chief function at present 

 seems to be to keep down the price of ammonium sulphate and 

 sodium nitrate. In a few years, however, it seems probable that 

 the demand for nitrates in other directions will increase to such 

 an extent as to render necessary a greatly increased production 

 of the artificial compound. We may now turn to the processes 

 by which atmospheric nitrogen is being brought into forms of 

 practical utility. 



Up to comparatively recent times gaseous nitrogen was 

 described in chemical text-books as a very sluggish substance, and 

 was often stated, quite improperly, to be incapable of entering 

 into chemical combination with other elements by any direct 

 method. It constitutes four-fifths of atmospheric air, and is 

 usually said to serve the purpose of diluting the oxygen of the air, 

 which would otherwise be too stimulant for the health of the 

 animals which live in it. There is a certain fallacy implied in this 

 statement. If an atmosphere of pure oxygen had been provided 

 as the outcome of the chemical changes which attended the early 



