r, by analysis, but an extremely small proportion of earth in
vegetable compounds.

CAROLINE.

But if earths do not afford nourishment, why is it necessary to be so
attentive to the preparation of the soil?

MRS. B.

In order to impart to it those qualities which render it a proper
vehicle for the food of the plant. Water is the chief nourishment of
vegetables; if, therefore, the soil be too sandy, it will not retain a
quantity of water sufficient to supply the roots of the plants. If, on
the contrary, it abound too much with clay, the water will lodge in such
quantities as to threaten a decomposition of the roots. Calcareous soils
are, upon the whole, the most favourable to the growth of plants: soils
are, therefore, usually improved by chalk, which, you may recollect, is
a carbonat of lime. Different vegetables, however, require different
kinds of soils. Thus rice demands a moist retentive soil; potatoes a
soft sandy soil; wheat a firm and rich soil. Forest trees grow better in
fine sand than in a stiff clay; and a light ferruginous soil is best
suited to fruit-trees.

CAROLINE.

But pray what is the use of manuring the soil?

MRS. B.

Manure consists of all kinds of substances, whether of vegetable or
animal origin, which have undergone the putrid fermentation, and are
consequently decomposed, or nearly so, into their elementary principles.
And it is requisite that these vegetable matters should be in a state of
decay, or approaching decomposition. The addition of calcareous earth,
in the state of chalk or lime, is beneficial to such soils, as it
accelerates the dissolution of vegetable bodies. Now, I ask you, what is
the utility of supplying the soil with these decomposed substances?

CAROLINE.

It is, I suppose, in order to furnish vegetables with the principles
which enter into their composition. For manures not only contain carbon,
hydrogen, and oxygen, but by their decomposition supply the soil with
these principles in their elementary form.

MRS. B.

Undoubtedly; and it is for this reason that the finest crops are
produced in fields that were formerly covered with woods, because their
soil is composed of a rich mould, a kind of vegetable earth, which
abounds in those principles.

EMILY.

This accounts for the plentifulness of the crops produced in America,
where the country was but a few years since covered with wood.

CAROLINE.

But how is it that animal substances are reckoned to produc