THE IMPERIAL ASPECTS OF CHEMICAL SCIEN CE. 
some object of commercial activity. The superiority of classical or 
humanistic over scientific studies, as instruments for the training of the 
intellect, lies in the freedom of the former from this taint. 
One of the most striking of the many Imperial aspects of chemical 
science is presented by the great question of the provision of nitrogen 
compounds. Every kind of living matter requires for its sustenance 
supplies of compounds which contain the element nitrogen in such a 
condition as to be assimilable by the living material. Even the most 
highly developed forms of vegetable life are capable of absorbing nitro- 
gen from the simple types of combination of the element as ammonia, 
salts of nitric acid, and urea. The higher animals are incapable of 
utilizing nitrogen presented in such simple combinations as these; they 
require nitrogenous food in the form of such complex compounds as the 
proteins or albumenoids which are present in other animals or in veget- 
able materials. The nitrogen thus absorbed by the animal leaves 
the living body by exeretionary or putrefactive. processes to reappear 
ultimately in the dead form of ammonia, nitrates, or urea. A kind 
of cyclic process is thus apparent in nature. The last-named simple 
forms of nitrogen compounds are extracted from the soil by vegetable 
life and elaborated into the complex nitrogenous protein suitable for 
assimilation by the animal; the animal returns this absorbed ‘nitrogen 
to the soil by excretion or putrefaction as simple nitrogen compounds 
which are once more available for the sustenance of vegetable life. 
The animal may, of course, serve as food for another animal such as 
man, but this step is not an essential one. The sheep, which we eat 
in the form of mutton, merely acts as a kind of “middle man,” passing 
the highly complex nitrogen compounds on from the vegetable factory 
to us; the devotees of vegetarianism claim that in serving this function 
the sheep behaves as a shameless profiteer. 
The contemplation of this nitrogen cycle makes it clear that, mainly 
in view of the enormous loss of excreted nitrogen, continuous supplies 
of simple nitrogen compounds must be provided. for the sustenance and 
propagation of the vast quantities of vegetable matter which all animals 
need to keep them alive. It is thus necessary to supplement the sup- 
plies of ordinary farmyard manure, which are useful only as providing 
nitrogenous compounds to vegetation, by other nitrogen compounds to 
replace loss and to meet the constantly increasing demands of a growing 
world population. ; 
Previous to the war the supplies of nitrogenous compounds thus 
called for were drawn in the main from the huge deposits of nitrates 
which occur as Chili saltpetre, and which represent the accumulation 
of ages of excretory and putrefactive products of bird life in- South 
America. During the few years before the war an average of some 
20,000 tons per annum of combined nitrogen were imported into Great 
Britain in the form of Chili saltpetre; approximately the same amount’ 
of combined nitrogen was reserved for home use annually from the 
ammonium salts produced during the production of illuminating gas 
from coal. It is clear, however, that the needs of the future will be 
enormously greater than those indicated by these figures. The late Sir 
William Crookes called attention to this in 1898, and pointed out that 
only by largely increased application of nitrogenous manures to the soil 
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