PREPARATION OF COMPOSTS. 
71 
tractable under the hand of art, a very near approach may be 
made to give them what is most congenial to them in the new 
station or circumstances to which they have been transferred. 
The florist, whether as a cultivator of hardy or exotic plants, 
requires to be very particular in forming his composts. Ex¬ 
perience, it is true, is our guide on these matters, and the design 
of this communication is to give some account of what practical 
botanists and gardeners have discovered and recommended on 
the subject of composts. It may be necessary to remark in the 
first place, that the food of plants exists chiefly in air and earth 
in the form of gas : this has been detected by chemists; the chief 
is carbonic acid gas, and though this chemical body be imper¬ 
ceptible to the sight, we have learned by experience in what 
substances it is generally found ; those substances are called 
manures, and are either vegetable or animal matter in a state of 
decomposition, and are well known to every cultivator. In 
forming composts, however, it is not only their nutritive quality 
which is to be attended to, but the consistence of the materials 
composing them. The roots of plants are differently constituted: 
some are extremely attenuated, others gross and substantial; 
some require a dense compacted bed to establish themselves in, 
others one that is porous and loose. It appears that air in the 
soil is as necessary to the roots as water, both of which are made 
of those gases on which the plants live, and without which 
they would die. In order that the cultivator may have every 
kind of earth and other matters required for forming his com¬ 
posts, his mould-yard should be furnished with heaps of the 
following materials: namely, loam dug from the surface of an 
old meadow ; turf stripped off a dry common where heath grows 
naturally; white or light-coloured sand; leaf-mould dust from 
the bottom of old faggot-piles ; decayed dung from old hotbeds, 
together with the dung and droppings of all domestic animals. 
There beingdifferentdepartmentsingardens, as thetropical stove 
or hothouse, the conservatory and greenhouse, the plants in these 
are generally grown in the same description of compost, which, 
with some exceptions, answers pretty well for the whole. I shall 
first give the general composts, and then speak of the tribes re¬ 
quiring peculiar soils. For the generality of hothouse plants a 
mixture of loam and peat earth is best; the mixture should be 
broken as fine as possible with the spade, but not sifted, for the 
lumps of turf give freedom to the roots as well as a free passage 
