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The ammonia given off from animal compounds 
in putrefaction may be conceived to be formed at 
the time of their decomposition by the combination 
of hydrogene and azote ; except this matter, the 
other products of putrefaction are analogous to 
those afforded by the fermentation of vegetable 
substances ; and the soluble substances formed 
abound in the elements, which are the constituent 
parts of vegetables, in carbon, hydrogene, and 
oxygene. 
Whenever manures consist principally of matter 
soluble in water, it is evident that their ferment- 
ation or putrefaction should be prevented as much 
as possible; and the only cases in which these 
processes can be useful, are when the manure con- 
sists principally of vegetable or animal fibre. The 
circumstances necessary for the putrefaction of 
animal substances are similar to those required for 
the fermentation of vegetable substances ; a tem- 
perature above the freezing point ; the presence of 
water, and the presence of oxygene, at least in 
the first stage of the process. 
To prevent manures from decomposing, they 
should be preserved dry, defended from the contact 
of air, and kept as cool as possible. 
Salt and alcohol appear to owe their powers 
of preserving animal and vegetable substances to 
their attraction for water, by which they prevent 
its decomposing action, and likewise to their ex- 
cluding air. The use of ice in preserving animal 
substances is owing to its keeping their temperature 
low. The efficacy of M, Appert’s method of 
preserving animal and vegetable substances, an 
