53

then, with the exception of its mineral constituents, entirely
disappear from the ground. This effect is, as we know, ac-
tually produced in the body of the soil to which stable ma-
nure is applied; our experience teaching us that, in the course
of time, no trace of it is left in the soil; but as this final
term of existence is, in no wise, intended to be reached at the
barn-yard, we may here freely dispense with its consequences
as no subject for discussion in this place. All that we desire,
for the present, to arrive at, is a knowledge of the changes
which stable manure undergoes by putrefaction at the barn
yard, or within a certain period of time previous to its being
applied to the soil. The pecularities of these changes will
best become apparent by a single comparison of the composi-
tion of stable manure, when in its fresh state, and after hav-
ing putrefied under necessary precautions. From the result
of direct analyses, the following conclusions may at once be
drawn:

1.  Water, carbonic acid and ammonia, being evolved in
the course of putrefaction, reduce the absolute weight of the
manure, and thus increase, relatively, the quantity of the in-
volatile portion, or its mineral constituents.

2.  There is relatively more of carbonic acid and water
evolved, and less of ammonia, than is in proportion to the
quantities of carbon, hydrogen, oxygen and nitrogen which
constitute the manure. The quantity of nitrogen is, there-
fore, relatively increased in the putrefied manure. And
finally:

3.  Inasmuch as a part of the oxygen has directly com-
bined with hydrogen and departed in the form of water, the
quantity of carbon became also relatively increased, and thus
effected a partial change of the original light color of fresh
stable manure into the brown, or even black color of that
which is putrefied.

These conclusions are very similar to those which we have
formerly expressed in relation to the composition of food
and excrements; the final products of both processes, of di-
gestion and putrefaction, being-richer in nitrogen and min-
eral matters than the original substances from which they
were derived,—the one process is quasi a continuation of the
other, both producing identical changes. Indeed, the ulti-
mate compositions of food and excrements, fresh stable ma-
nure and putrefied barn-yard manure, bear exactly the same
relation to each other, and prove, besides, that in each case
an entirely new article is produced, provided with specific
virtues of its own. Thus barn-yard manure, when putre-
fied, differs materially from fresh stable manure in composi-