292 HOW CROPS FEED. 
gault, in his investigations on the assimilability of free 
nitrogen, found in various vegetation-experiments, in 
which crushed seeds were used as fertilizers, that nitrogen 
was lost by assuming some gaseous form. This loss prob- 
ably took place to some slight extent as ammonia, but 
chiefly as free nitrogen. Lawes, Gilbert, and Pugh, found 
in thirteen out of fifteen trials, including the experiments 
just referred to, that a loss of free nitrogen took place, 
ranging from 2 to 40 per cent of the total quantity con- 
tained originally in the vegetable matters submitted to 
decomposition. In six experiments the loss was 12 to 13 
per cent. In the two cases where no loss of nitrogen oc- 
curred, nothing in the circumstances of decay was discov- 
erable to which such exceptional results could be at- 
tributed. Other experiments (Phil. Trans. 1861, IL, p. 
509) demonstrated that in absence of oxygen no nitrogen 
was evolved in the free state. 
c. Nitric acid is not formed from the nitrogen of or- 
ganic bodies in rapid or putrefactive decay, but only in 
slow oxidation or eremecausis of humified matters. 
Pelouze found no nitrates in the liquor of dung heaps. 
Lawes, Gilbert, and Pugh, (/oe. cié.).found no nitric acid 
when the seed-grains decayed in ordinary air, nor was it 
produced when ozonized air was passed over moist bean- 
meal, either alone or mixed with burned soil or with 
slaked lime, the experiments lasting several months. It 
thus appears that the carbon and hydrogen of organic 
matters have such an affinity for oxygen as to prevent the 
nitrogen from acquiring it in the quicker stages of decay. 
More than this, as Pelouze has shown (Comptes Rendus, 
XLIV., p. 118), putrefying matters rob nitric acid of its 
oxygen and convert it into ammonia. We have already 
remarked that putrefaction and fermentation are reducing 
processes, and until they have run their course and the 
organic matters have passed into the comparatively stable 
forms of humus, their nitrogen appears to be incapable of 
