osphere. Facts in
support of this theory are abundant.

A trial was made to ascertain whence comes the matter of which a tree is
composed. A quantity of kiln-dried earth was weighed and then put into a
tight vessel. A willow shrub was also weighed and planted in that earth,
and the vessel covered with perforated tin to keep out the dust; for a
year and a half it was supplied only with pure water. The tree was then
taken out, and found, by weight, to have gained one hundred and sixty
pounds. The earth was then kiln-dried, as before, and weighed, and its
weight was found to be only two ounces less than it was a year and a
half before, when it was deposited there. The tree, then, must have
received its growth, not from the soil, but from the water or the
atmosphere, or both.

Another fact: take a load of manure, dry it thoroughly, and weigh it.
Then moisten it and apply it to the soil, and it will increase the
weight of vegetation from ten to thirty or forty times its own weight
when dry, and yet most of that manure may still be found in the soil.
Hence it can only feed plants in a very limited degree. Its action must
be on air and water, or the control it gives the soil over those
elements.

It is also matter of common observation that soil well manured, will
continue moist for a long time after similar land by its side, but which
has not been manured, is dried up. Hard coarse soils dry up very
quickly, while soft, mellow, and friable ones will endure a long
drought. The gases and moisture generated by the decomposition of
manures produce this mellow state. Hence the necessity of having that
decomposition take place under the soil, or of plowing in the manure.

Another important fact bearing on this question is, that what are
regarded very poor soils, such as light sandy or gravelly land, will
produce good crops in a season remarkable for the frequency of showers.
On such soils crops are from twice to four times as large, in a wet
season as in a dry, and yet there is an addition of nothing but
moisture, and in such a manner, as not to have it stand and become
stagnant among the roots of the plants.

Yet another evidence is in the strength of clay soils. A hard clay is
very unproductive. But so disintegrated that plants can grow in it, it
produces a great crop. This is because clay is of so close a texture,
that when mixed with manure, turf, sand, or muck, although friable, it
retains more moisture, than sand or ordi