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juices, gum, sugar, starch, acid, gluten, albumen, (the last two
being the nutritive principle of wheat, corn, &c.) yet they are of
no more use than certain other substances, which are of equal ne-
cessity to the animal, and are always present in productive soils,
and in a form, state, or condition capable of being taken up by
the plant. These essential elements are                                     

INORGANIC OR MINERAL MATTERS.

Silica, Silicious Earth, or Sand—Which is the oyxd of
Silicon, exists abundantly in all soils. Though having none of
the sensible properties of an acid, it nevertheless belongs to this
class of bodies, and combines with bases to form salts. It very
rarely exists in a pure form in the earth, being almost always in
union with some other substance, and forming a class of bodies
called silicates. With alumina and peroxyd of iron, it forms our
red and yellow clays; it most generally is associated with lime,
magnesia, potash, or soda. The "grains of sand" in soils, are fre-
quently composed of pure sand (silicic acid) in combination with
some of the above substances. In pure water, these combinations
are quite insoluble; but water charged with carbonic acid dissolves
them in a sensible degree. When first set free from its combina-
tions, water dissolves it very readily.                                       

Besides its determining, to a great extent, the mechanical proper-
ties of soils, and when in a very fine state of division, acting as a
substitute for iron and clay in their absorbent capacity; it has a di-
rect and independent use, that of forming the stalk and stem of
plants, and the husk or outward envelope of the grain. In combina-
tion with potash, soda, lime and magnesia, but more particularly
with potash, it gives hardness and firmness to the stalk of grasses,
Indian corn, wheat, rye, oats, &c. It gives strength to the stalk to
support the weight of the blades and ear; forms channels for the cir-
culation of the sap, and for the transmission from the root, of what-
ever nutriment the other parts of the plant may require. Without
the presence of this substance, and that too in a suitable state to be
taken up by the roots, whatever quantity of the other constituents of
plants might be present in the soil, vegetation could not arrive at
any perfection. If the materials for the grain or ear existed, still
there would be no stalk to support them.

The soils which, in common parlance, are called "sandy soils,"
frequently contain no more sand than those which are called
"white oak soils, or pipe clay soil."

The difference in their texture is due to the size of the individ-
ual grains of sand, and not to the quantity which actually exists
Other things being equal, the finer the grains of sand the better