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i'i; !
I I
U . " III
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witli sufficient accuracy to enable them to depend on tlic result : but still, such a know-
Icdo-c of clieinistry as shall enable the cultivator to understand the nature of the process
and its results, when made and presented to liiin by others, is likely to be higlily useful,
and ouo-ht to be acquired by every man whose object is to join theoretical to practieiU
knowledge. I f it so happens that he can perform the operations of analysis Imnself, so
much the better, as far as that point is concerned ; bnt, on the whole, such knowledge
aud adi-oitncss m-e not to he expected from men who have so many other points dc-
mandiii«- thcir attention, and who will, therefore, effect thcir pmposc much better by
collecting proper specimens of the soils to be studied, aud sending them for analysis to
an operative chemist. ^ ^ a • t
1189. In selecting specimens, where the general nature of the soil is to be ascertained,
portious of it should be taken from different places, two or tlirce inches below the surface,
and examined as to tlic similarity of thcir properties. I t sometimes happens, that upon
plains, the whole of the upper stratum of the land is of the same kind, and m this case,
ono analysis wül be sufficient : but in vaUeys, and neai- tbe beds of rivers, there are very
great differences, and it now and then occm-s that one part of the surface is calcareous,
and another part siliceous ; and in this case, and in analogous cases, the portions different
from each other should be separately submitted to cxpeiiment. Soils, wlicn
collected if they cannot be immediately examined, should be preserved m phials quite
tilled with them, aud closed with ground glass stoppers. The quantity of soil most
convenient for a perfect analysis is from two to four hundred gi-ains. I t shotüd be collected
in dry wcatlicr, and exposed to the atmosphere tiU it becomes dry to the touch.
1190 The most fertile soils arc those which contain the greatest m ixture of eai'ths ; but
when soils arc to be adajptcd to particular plants, particulai- kinds of earth ave found to
be requisite according to the natm-e of the plants ; and what these caitlis ai-e can only
be ascertained by bm-ning different plants and examining their ashes.
1191 “ When we examine the ashes o f plants,” says Sclilciden, “ we find in paiticular
the four foUowing constituents, giving them thcir characteristics : readUy soluble alkaline
salts: earths, especially lime and magnesia; phosphoric acid, and sUicicacidor sficx.
Sometimes one, sometimes two of these substances predominate in the ashes of the plant.
According to this, Liebig divides the cultivated vegetables into : 1. Alkali plants ; to
which belong potatoes and beets. 2. Lime plants ; clover, peas, &c. 3. Sfiex plants ;
the c^i-asscs. 4. Phosphorus plants ; comprehending rye and wheat. But besides
these which arc only the general outline, plants have been found to contain various
other earths or salts, sometimes to the nmnber of five or six different lands, in very smaü
U 9 Î ^ “ ^r/ie saline matters in the soil,” observes Professor Solly, “ arc principally the
sulnhatcs, muriates, nitrates, and phosphates, of the alkaline and eai-thy bases. The
nature and quantity of these substances vary considerably, but they never constitute
more than a very smaU portion of the soil ; their influence upon vegetation is, however,
considerable, for certain plants seem to require particular saline substances, and do not
gi-ow well in soils not containing them.” _
1193 The relative proportion o f the ingredients o f soils vai-ies very greatly. According
to the analyses given in Dr. Sprcngel’s book on the Composition of Soils, and quoted by
Professor Solly, it appears that silica in the form of sand constitutes above nine tenths ot
some of the most fcrtUc soUs in Germany. The other constituent parts of one of these
soils, according to Dr. Sprengel, were as foUow : humus, containing mti-ogen, humic
acid, oxides of iron and manganese, aliunina, magnesia, lime, chiefly combined with
the silica, phosphoric acid, potash, soda, sulphuric acid, and a vei-y small proportion of
^^1194.’ Use o fth e result o f analysis. In the present state of chemical science, Dr. Ure
obsen'es, no certain system can be devised for the improvement of lands, mdcpcndent of
experiment; but there ai-c few cases in which the labour of analytical triMs will not be
amply repaid by the certainty with which they denote the best methods of melioration;
and this will particulai-ly happen, when the defect of composition is found m the proportions
of the different earths. In supplying organic matter, a temporary food only
is provided for plants, which is in aU cases exliausted by means of a certam number ot
crops; but when a soil is rendered of the best possible constitution and texture, with
regard to its earthy parts, its fertility may be considered as permanently established. I t
becomes capable of atti-acting a very largo portion of vegetable nomishmeiit from the
atmosphere, and of producing its crops with comparatively little labour and expense
(Diet, o f Chem., art. Soil), by stirring the soil, and a proper succession ot crops.
Subsect. 3. O f discovering the Qualities o f a Soil mechanically and empirically.
1195. The physical properties of soils, and some of thcii- most important constituents
rclativciy to the cultivator, may be ascertained to a certain extent by various and very
simple means.
any acid on it, and observing if T c f tW e s L s f L e i r ^ l L L a Z Z 7 i s f f i T b I f““ ?®
to receive a solK ityapproacl^^^^^ to tliat which they possessed when first obtai ed for
Sect. V. O f the Improvement o f Soils.
vei-isnZn ^ l> y e n M more f i t fo r answering the purposes o f veqeta&m hy pnl-
vciisation by consolidation, by exposure to the atmosphere, by an alteatio n of their
COTis itnent parts by ehanging tlieir condition in respect t ! L Z q b r d lT g i n i * 7
Lltiv a tcd AU tbes" inflkcnco, and by a change in the kinds of plants
cultivated. AU these improvements are mdcpendent of the appUcation of manm-es!
SuBSECT. I . _
a. ioi/s, ‘f ’to t/ieptfriabk by culUvtUum, won become hardmeil on the surface. Even