190 ON THE DISCRIMINATION OF SOILS^ 
of one-tliird would be abstracted, and the mass become proportion ably meliorated. 
A young active chemist, alive to the charms of horticulture, could effect wonders 
with his soils. We^, of course, speak of those intended for pot cultures, wherein a 
barrow, with the aid of vegetable soils, &c., goes a great way. 
The quantity of vegetable matter which exists in any soil may be pretty accu- 
rately determined by burning ; that is, by keeping a known weight of it at a red 
heat, till it retain no blackness upon becoming cold. Vegetable matter is essential 
to the fertility of a soil ; and, therefore, if a loam which is found to contain the 
staple earths above-mentioned in fair proportion, and is of a good free- working j 
texture, be very deficient in decomposable matters, it must be enriched with leaf 
mould, decayed vegetable mould, or completely reduced manure. 
The best substitute for a perfect natural loam, is the reduced grass turf of a 
meadow or common. Vegetable matters, it is probable, are resolvable by decay in 
earth very similar in quality to that upon which they grow ; and when short grass 
turf is cut into thin layers, it will, in a short time, become a fine mould. The 
turfs, not thicker at first than an inch and a half, should be piled in a heap, the 
grass face downward, and be kept so for two or three months. They should then 
be chopped to pieces, turned, and thoroughly incorporated ; and these processes are 
to be repeated, at intervals, till the whole become a mass, replete with tender j 
vegetable fibres. Such a soil, at the end of a year, will prove a valuable substitute i 
for good native loam, and be available for every purpose of the gardener. A stock 
ought to be prepared every year. | 
We will now dismiss the consideration of loam, hoping that a certain degree of ^ 
experience will teach the Horticulturist the real value of chemistry. He, by the 
aid of a few books, and a little patient assiduity, will acquire a tact ; and his 
pleasure will be much enhanced by the confidence his mind will acquire. None 
but the ignorant scoflT at knowledge ; the enlightened mind feels indeed, and is 
sensible of, its own imperfections ; but it possesses that which no one can have any 
conception of but he who has it. 
Sand is another substance of the components and qualities of which most are 
entirely ignorant ; as, however, the cultivator of exotics in pots requires only a few 
sorts of sand to enable him to strike cuttings, and to give openness of texture to his 
soils and composts, we shall mention but two species ; the first is that fine, pure, 
siliceous substance termed silver or writing sand ; some of this ought always to 
be at hand ; and where pit sand only can be obtained, we recommend that it be 
washed repeatedly till it cease to yield any considerable quantity of light, earthy j 
matter to water. That clear, heavy substance which precipitates in a second or 
two, leaving the water void of colour, is sharp enough for the purposes of striking 
cuttings, and blending with loam and vegetable earth. 
The second sort of useful sand, is the drift of a road, that has been carried 
down by rain ; this is next in value to river sand, and may be procured readily 
where that is wholly unobtainable. I 
In some districts these coarse sands are very compound in their nature ; they !I 
may contain lime, alumen, and iron, but in a state of chemical union which renders 
them nearly insoluble. In gravelly districts, road and river sand are the reduced, 
washed fragments of abraded gravel stones ; they consist chiefly of flint, coloured 
