51               

2. The absolute quantity of carbon, hydrogen, oxygen and
nitrogen in the excrements, is less than their absolute quan-
tity in the food.

3. The absolute quantity of mineral matters is equal to that
contained in the food.

4.  The per centage (or relative quantity) of mineral mat-
ters in the excrements is higher than in the food; and
finally,

5.  The per centage of nitrogen (that substance which is
capable of producing ammonia) is also higher (about double)
in the excrements than in the food.

This much as to the relations between food and excrements,
so far as they are founded on the ultimate composition of
both, us well as on the peculiar changes to which the food is
subjected in the animal body. With it we now leave the
matters as they occur in the living animal, under the influ-
ence of the vital powers, to themselves, and turn next our
attention to the changes which occur in the excrements when
without the animal body and exposed to the influence of at-
mospheric air; I mean to say, to the changes they undergo
by the process of putrefaction.

The excrements of animals soon become intimately mixed

with the litter straw of the stables, and remain in this state,

at the barnyard, sometimes for months, before being applied

to the soil as manure. The reasons for such a delay in the

application are, in no wise, to be attributed to a negligence

on the part of the farmer, nor are they altogether conditioned

by the necessity to await the proper season for manuring. A

rational husbandman, one who works understandingly, is

besides well aware of the fact that barn-yard manure, in its

different phases of putrefaction, will exercise very different

effects on a particular kind of soil, and knows by experience

how far its decomposition has to advance to suit best the soil

to which he intends applying it.

It is a well known fact that organic bodies, over which the
vital powers have ceased to exercise a control, becoming ex-
posed to the simultaneous influence of air, moisture and heat,
will decompose and consequently decay. We say they are
rotting," if no stinking effluvia be evolved from them; and
this is the case with all those which are composed of no other
elements but carbon, hydrogen and oxygen. Wood-fibre, of
which the principal mass of plants is made up, is a represen-
tative of this class of organic matters, and its decay consists
simply in a slow combustion, (eremecausis,) produced by its
uniting with atmospheric oxygen. Under these circumstan-
ces, carbon and hydrogen, the constituents of the fibre, become