ed,
soluble matters are carried away by the water, which is often dark-brown
from the substances dissolved in it. Finally the soil of the adjacent
land is washed or blown upon the swamp, in greater or less quantities.

III.--_The decomposition of peat in the soil offers some peculiarities_
that are worthy of notice in this place. Peat is more gradual and
regular in decay than the vegetable matters of stable dung, or than that
furnished by turning under sod or green crops. It is thus a more steady
and lasting benefit, especially in light soils, out of which ordinary
vegetable manures disappear too rapidly. The decay of peat appears to
proceed through a regular series of steps. In the soil, especially in
contact with soluble alkaline bodies, as ammonia and lime, there is a
progressive conversion of the _insoluble_ or _less soluble_ into
_soluble_ compounds. Thus the inert matters that resist the immediate
solvent power of alkalies, absorb oxygen from the air, and form the
humic or ulmic acids soluble in alkalies; the humic acids undergo
conversion into crenic acid, and this body, by oxidation, passes into
apocrenic acid. The two latter are soluble in water, and, in the porous
soil, they are rapidly brought to the end-results of decay, viz.: water,
carbonic acid, ammonia and free nitrogen.

Great differences must be observed, however, in the rapidity with which
these changes take place. Doubtless they go on most slowly in case of
the fibrous compact peats, and perhaps some of the lighter and more
porous samples of swamp muck, would decay nearly as fast as rotted
stable dung.

It might appear from the above statement, that the effect of exposing
peat to the air, as is done when it is incorporated with the soil, would
be to increase relatively the amount of soluble organic matters; but the
truth is, that they are often actually diminished. In fact, the
oxidation and consequent removal of these soluble matters (crenic and
apocrenic acids,) is likely to proceed more rapidly than they can be
produced from the less soluble humic acid of the peat.

IV.--_Comparison of Peat with Stable Manure._

The fertilizing value of peat is best understood by comparing it with
some standard manure. Stable manure is obviously that fertilizer whose
effects are most universally observed and appreciated, and by setting
analyses of the two side by side, we may see at a glance, what are the
excellencies and what the deficiencies of peat. In ord