FIXATION OF ATMOSPHERIC NITROGEN 395 



pointed out that if nitrate were used alone the available minerals 

 such as potash and phosphate would soon show a deficiency. 



There can be no doubt as to the benefit derived from the use 

 of nitrogenous manures, but there can also be no doubt that in a 

 comparatively few years the supplies of natural nitrate are 

 certain to be exhausted. This substance occurs in the rainless 

 district in the northern provinces of Chile between the Andes and 

 the coast. In recent times of peace the exports ot nitrate from 

 Chile are stated to have risen from the estimated 1,200,000 tons 

 in 1898 to more than double that amount per annum. Into the 

 United Kingdom alone the imports, according to the Board of 

 Trade returns, have been as follows : 



Year. Tons. Value. 



1909 .. 90,207 .. 860,860 



1910 .. 126,498 .. 1,161,127 



1911 .. 128,487 .. 1,189,019 



1912 .. 123,580 .. 1,274,752 



1913 .. 140,926 .. 1,490,669 



figures which show a gradual increase of price. The consumption 

 of nitrates during the war must be enormous, and probably 

 exceeds the total consumption for agricultural purposes. 



Looking to other available sources of combined nitrogen the 

 next in importance is the ammonia derived from the nitrogen of 

 coal and employed in the form of sulphate. 



Animal manures come next, and in the form of the dung of 

 animals, fed on pasture, a certain amount of the nitrogen derived 

 from the grasses and other herbage is transferred to the arable, 

 including wheat lands. It is impossible in this connection to 

 avoid deploring the sewage system which is so generally prevalent 

 in towns and cities, for by this means practically the whole of 

 the nitrogen from the food of the human population is irrecover- 

 ably wasted. A simple calculation will show how very great is 

 the waste. Assuming that in round numbers there are 30 million 

 adults and 15 million children in the United Kingdom, and that 

 each adult excretes 1 ounce of urea and a child | ounce of urea 

 in a day, these figures correspond to 381,790 tons of urea in the 

 year. This quantity of urea contains the same amount ol 

 nitrogen as 839,942 tons of ammonium sulphate or 1,081,744 tons 

 of sodium nitrate. A small quantity of this nitrogen passes 

 direct to the soil and a small quantity to sewage farms, but the 



