at food can enter into the structure of the plants;
it should be sufficiently retentive to avoid the risk of injury by reason
of the evaporation, which takes place to a very great extent, when too
great an abundance of silica is present, or when more than a due degree of
porosity exists in its mechanical texture; and it should be sufficiently
permeable, to prevent any thing like excess of moisture, by stagnation.

Soils composed either principally, or almost entirely of heath soil, or of
vegetable mould, although very highly recommended for the growth of the
Cucumber in winter, are nevertheless objectionable when applied alone, as
will be evident if the foregoing principles are taken into view: it cannot
however be assumed that the plants will not grow in these soils, for they
grow vigorously for a period; neither can it be asserted that such soils
do not contain the qualities which are necessary to administer to the
nutrition of plants, for it is scarcely possible to conceive any
substances which are more nutritious, or whose application in this respect
is more effectual; but they are objectionable, in consequence of their
becoming soon expended, and failing to maintain for any length of time, an
equable degree of moisture. The cause which tends to produce this effect,
is the porosity, or the want of mechanical combination in the texture of
the soil; which being highly favourable to evaporation, is liable to
render it speedily, and very materially dry, when exposed to the influence
of powerful solar heat: the frequent application of water, does not
entirely obviate the objection, for even when so applied, it soon becomes
again evaporated, and thus tends to deteriorate the soil, and decrease its
fertility; this it does, by taking up much of the soluble matter contained
in it, and conveying it by evaporation into the atmosphere, instead of its
being taken up by the roots whilst in a fluid state, and applied to the
plant as a means of nutrition: when it is thus conveyed to the atmosphere,
the leaves though they are enabled to take up a portion of their food from
thence, are still incapacitated to do so fully, and hence, much of the
fertilizing properties of the soil, is carried off by the first current
of air which passes through the structure; and the plants decline by
reason of starvation, though they had been seated in the midst of plenty.

The soil which I should recommend for the growth of the Cucumber, would be
compo