ally employed. In many cases a
good peat or muck is the best form of this material, that lies at the
farmer's command.

I.--_Its absorbent power for liquid water_ is well known to every farmer
who has thrown it up in a pile to season for use. It holds the water
like a sponge, and, according to its greater or less porosity, will
retain from 50 to 100 or more _per cent._ of its weight of liquid,
without dripping. Nor can this water escape from it rapidly. It dries
almost as slowly as clay, and a heap of it that has been exposed to sun
and wind for a whole summer, though it has of course lost much water, is
still distinctly wet to the eye and the feel a little below the surface.

_Its absorbent power for vapor of water_ is so great that more than once
it has happened in Germany, that barns or close sheds filled with
partially dried peat, such as is used for fuel, have been burst by the
swelling of the peat in damp weather, occasioned by the absorption of
moisture from the air. This power is further shown by the fact that when
peat has been kept all summer long in a warm room, thinly spread out to
the air, and has become like dry snuff to the feel, it still contains
from 8 to 30 _per cent._ (average 15 _per cent._) of water. To dry a
peat thoroughly, it requires to be exposed for some time to the
temperature of boiling water. It is thus plain, as experience has
repeatedly demonstrated, that no ordinary summer heats can dry up a soil
which has had a good dressing of this material, for on the one hand, it
soaks up and holds the rains that fall upon it, and on the other, it
absorbs the vapor of water out of the atmosphere whenever it is moist,
as at night and in cloudy weather.

When peat has once become _air-dry_, it no longer manifests this avidity
for water. In drying it shrinks, loses its porosity and requires long
soaking to saturate it again. In the soil, however, it rarely becomes
air-dry, unless indeed, this may happen during long drouth with a peaty
soil, such as results from the draining of a bog.

II.--_Absorbent power for ammonia._

All soils that deserve to be called fertile, have the property of
absorbing and retaining ammonia and the volatile matters which escape
from fermenting manures, but light and coarse soils may be deficient in
this power. Here again in respect to its absorptive power for ammonia,
peat comes to our aid.

It is easy to show by direct experiment that peat absorbs and combines
with amm