246 THE CHEMISTRY OF SOILS AND MANURES. 
As soon, however, as the setting process is over, they will bear a moist atmosphere, provided 
plenty of air is given ; hut for veiy early forcing great caution must he used in watering, — water- 
ing only where it is needed. They are sure to go blind if they are carelessly watered early in the 
season. 
As the season advances they will require a great deal of water, and as soon as the fruit is set they 
are greatly benefited by being watered every other time with weak liquid manure ; but this must be 
discontinued as soon as the fruit begins to colour. I do not like putting the pots in saucers, but where 
the plants are forced in vineries on shelves on the back wall, it is a good plan to prevent their drying 
so very quick, to place something up in front of the pots, which shall not be high enough to shade the 
plants, but which will preserve the roots from being scorched through the pots. They should never 
be more than eighteen inches from the glass, and have plenty of light. I never put more than one 
plant in a pot (No. 24), and by following the above system as near as circumstances will permit, I have 
frequently picked 8, 9, and 10 oz. from one pot, which is not a bad crop. I find the Keene's seedling and 
Alice Maud force best ; the British Queen is very good for a late crop, but it is not nearly so profitable 
as the two first mentioned. 
THE CHEMISTRY OE SOILS AND MANURES. 
Br Dr. A. VOELCKEE, Professor of Chemistry in the Royal Agricultural College, Cirencester. 
ON THE CLASSIFICATION OF SOILS. 
I 
! 
fjF any person could with one coup a" mil observe the various soils found in different places over the 
earth's surface, the comparison of some of them would afford many striking diffei-ences and pecu- 
liarities, in respect to position, thickness, extent, agricultural capabilities, and other properties, whilst, 
at the same time, many would be found so slightly differing from each other, that he would experience 
much difficult}' in discriminating between them, though, on minute investigation, their characters 
would be found differing in many respects. Distinct lines of demarcation are nowhere found, which 
might assist us in the characterising of the several classes of soils. This difficulty, which opposes itself 
to a simple and good arrangement of soils, is greatly increased by the vague manner in which soils 
are frequently described by agricultural writers, and the various acceptation of such terms as hazel- 
loam, brown loam, clayey loam, fat soil, sandy soil, humus soil, garden mould, &c, in different parts 
of the country. The want of a proper definition of these and other terms is so perplexing, and the 
meaning which people in different localities attach to them, so variable, that it is difficult for the 
gardener who reads a description of a soil, in which a certain plant best succeeds in another country, 
to judge what relation this soil bears to his own. 
Soils in general consist of a mechanical mixture of the following four substances : — 1. Silica, 
silieious sand and gravel. — 2. Clay. — 3. Lime. — 4. Animal and vegetable remains (humus). Few 
soils are found to consist altogether of one or two of these four substances : most contain them all, hut 
the relative proportion of each in different samples varies considerably ; and as just on this relation 
the fertility, agricultural capabilities, and other characters mainly depend, a natural division may 
be founded on the preponderance of one of these four chief constituents. 
Upon this principle soils may be conveniently classified as follows : — 
1. Sandy soils, containing above eighty per cent, of silieious sand. 
2. Calcareous soil, containing above twenty per cent, of lime. 
3. Clay soils, containing above fifty per cent, of clay. 
4. Vegetable moulds (humus soils), soils of various composition, containing always more than five 
per cent, of organic matter. 
5. Marly soils, in which the proportion of lime is more than five per cent., hut does not exceed 
twenty per cent, of the whole weight of the dry soil, and that of clay is rnoi'e than twenty, but less 
than fifty per cent. 
6. Loamy soils, in which the proportion of clay likewise varies from twenty to fifty per cent., but 
which contain at the same time less than five per cent, of lime. 
I. Sandy soils. — They are generally of a loose, friable, open, dry character, and for that reason 
more easily cultivated, and with less expense, than any other. Many consist almost entirely of sili- 
eious sand and gravel, with but little alumina and calcareous matter. Such soils are almost absolutely 
barren and in general termed hungry, from their tendency to absorb manures, without any corre- 
sponding benefit to the land. Others, containing a larger proportion of alumina and lime, which 
render them more compact, and always more fertile. On these richer kinds of sandy soils, beans, peas, 
S ^W3 S^g JKl 
