174 Bacteria in Relation to Country Life 



Owing to the warm climate, the decay of the organic 

 matter must have proceeded very rapidly, while the 

 absence of rain prevented the nitrate formed from being 

 leached out and carried away in the drainage of the 

 country. The natives of Peru and Chile have known 

 the agricultural value of the nitrate for a long time, 

 and have probably used it to stimulate plant growth. 

 The first ship-load of nitrate of soda was taken to 

 England in 1827. Another was taken there in 1830, 

 but there was scarcely any demand for it on account of 

 the high price. As its value in agriculture and in the 

 chemical industries was recognized, the demand for it 

 increased rapidly until in 1903 it showed a consumption 

 of 1,429,150 tons, including the 264,000 tons brought 

 to the United States. 



Considerable quantities of nitrates, particularly 

 nitrate of potash, are also derived from other sources. 

 After the rainy season, portions of the plains of the 

 Ganges river in East India, become covered with a 

 deposit of white crystals consisting largely of nitrate of 

 potash. Evidently, the abundant moisture and favorable 

 temperature encourage the vigorous development of the 

 nitrifying bacteria, and a rapid production of the nitrates 

 of lime, magnesia and potash. As the moisture brought 

 up by capillary action from the subsoil is evaporated at 

 the surface, the nitrates it contains are left behind 

 in crystalline form. The nitrates of lime and mag- 

 nesia have, however, a great affinity for water-vapor, 

 which they absorb from the air, and do not, therefore, 

 crystallize out to the same extent as the nitrate of 

 potash. 



