170 
THE CULTIVATOR. 
examine in soils; 2d, the relative value of each of these 
characters ; and, 3d, their application to classification. 
§ I. The Characters of Soils in relation to Agriculture. 
When an agriculturist devotes himself to the investi¬ 
gation of a soil, it is a matter of indifference to him 
whether it is composed of alumina or silica, or whether !| 
these substances are in the state of quartz or felspar, or 
that by their aggregation they form the debris of gra¬ 
nite, or finally, that they belong to primitive, transition, 
or alluvial formations: what he requires, is to know 
what kind of plants the soil will produce with the great¬ 
est advantage, the trouble it will require to put it in a 
state of culture, the manuring it will need, the quantity 
of this manure it will yield to the plant, and the portion 
it will retain in its own substance, these are its agrcultu- 
ral characters,—those which adapt it to the objects of 
agronomy, and which shed light on his researches. 
What we have already said of the composition and 
properties of soils, demonstrates that certain of their 
scientific elements have a relation to the properties 
which are inquired after by agriculture. Thus, as to the 
nature of the crops which may be expected from diffe? 
rent soils, those which contain carbonates of lime and 
magnesia are eminently qualified to produce wheats and 
leguminous crops; the siliceous clay-lands are the soils 
peculiarly adapted to forests; the siliceous are proper 
for plants which vegetate in winter, as rye, &c.; mould 
favors the vegetation of those pot-herbs which are cul¬ 
tivated for the stems, leaves, &c. As regards the faci-! 
lity or difficulty of working soils, those that are silice¬ 
ous are easily dressed, as well as those which have an 
organic origin; whilst calcareous and clayey present 
great differences in this respect, according to the diver¬ 
sity of their composition. Finally, sandy and calcare¬ 
ous soils require frequent manuring, and this addition 
they decompose to the immediate profit of the plants, 
whilst clayey ones retain the manure, may have the 
process of manuring postponed to greater intervals, and 
receiving at the same time a larger quantity of manure. 
Diluvian soils admit of improvement with gypsum, and 
siliceous clays with marl; whilst lands rich in organic 
matters require the dung of animals to facilitate and 
promote the decomposition of the mould. 
Thus, we find in the mineralogical characters we have 
examined in detail, whether physical or geological, cer¬ 
tain relations with the agricultural characters. There 
are whole groups of soils whose natural characters an¬ 
swer to those agricultural characters, and reproduce pro¬ 
perties which are common to them all. After having 
recognized and distinguished them, we must next recog¬ 
nise those of them which from their importance and ge 
nerality will most naturally form the primary groups. 
§ II. Relative Value of Characters. 
_ For the appreciating of the relative value of the ag¬ 
ricultural characters which we have enumerated, it is 
necessary to discover which amongst them is the most; 
indispensable, and those whose absence would be most 
hurtful to agriculture; the degree of their importance 
and necessity will then indicate the relative subdivi¬ 
sions. 
The appropriation of lands to the different kinds ofj 
cultivation seems to possess these qualities in the high¬ 
est degree; and here, in fact, must begin every kind of 
agricultural improvement. It is only after having des-' 
tined a particular soil to an appropriate culture, that: 
we can begin to consider the labor and improvement it 
requires. These labors and improvements will be with-! 
out an object and a bearing, if we are still ignorant of| 
the plant to which they would be useful. And, more-| 
over, this investigation of the appropriation of soils to| 
particular cultures, is connected with the most natural 
classification, in a mineralogical point of view; it breaks 
the smallest number of affinities, and consequently ren¬ 
ders the determination of soils more easy and more sa¬ 
tisfactory. 
The labor required for bringing the soil into good 
working condition, is also a matter of great importance; 
for if the appropriation of soils decides the phytologi- 
cal or botanical part of the question as to cultivation, 
this other consideration bears on the question of econo¬ 
my. It modifies the plan of regulating the soils which 
might be determined on from the first consideration? 
taken by itself: it has also a very decided influence up-| 
on the choice of the means to be employed in overcom-|| 
ing the resistance upon the number and kind of animals,! 
and upon the implements to be procured. But were! 
this circumstance taken as the primary basis of the clas-| 
sification, we should then break all the natural affinities! 
of soils; for all the mineralogieal kinds are, in a great? 
er or less degree, susceptible of tenacity. Besides, it is 
evident that this greater or less degree of facility in 
working soils, dissociated from their capability of pro¬ 
ducing the most useful plants, is a quality of very little|i 
value ; that it is of no great moment, for example, thatfj 
we can easily labor a dry sand, and a rich marl only! 
with difficulty; and that, in short, in the examination off 
an estate, it is the character of the plants we inquire! 
considered in soils, in the following method:—1st, The 
appropriation of soil to plants ; 2d, the tenacity of the 
ground; and 3d, the aptitude of the soil to receive cer¬ 
tain kinds of manures or improvements. 
§ III. Primary Classification of Soils after their appro¬ 
priation to particular cultures. 
The Cerealia are every where throughout Europe 
the basis of rural operations. They succeed more or 
less in all the soils which supply them with a firm sup¬ 
port, and which at the same time allow the air to pene¬ 
trate to their roots; ranging from sandy soils which do 
not contain less than 80-100 of sandy or rocky materials, 
to stiff clays, provided that thesoils do not contain 2-100 
of sea-salt, or any sulphate of iron. The soils or pure 
mould are also excluded from this kind of cultivation, 
from the defective cohesion of their elements, and their 
frequent change of volume. Allowing for these excep¬ 
tions, there are three principal groups of soils. 1st, 
the saliferous; 2d, the sandy, which contain even as 
much as 8-10 of sand or of rock; and, 3d, organic soils, 
which contain | of mould. This division, it should be 
remarked, agrees not only with the results of the mine¬ 
ralogical study of the soil, but also with its tenacity; 
and hence it is perfectly natural. 
There remains, moreover, a great number of soils in 
which wheat thrives, when they contain, besides, a suffi¬ 
cient quantity of organic matter; but they are not all 
equally favorable. For its successful cultivation, those 
which contain only silex and clay must have lime added, 
a principle without which they will scarcely yield any 
return. As soon as this is supplied, their product im¬ 
mediately increases in a remarkable manner, to the ex¬ 
tent of a fourth, a third, and even a half. The vegeta¬ 
tion of the Cerealia, therefore, indicates a grouping 
which subdivides lands into soils containing carbonates 
(of lime or of magnesia, the latter supplying the place 
of the former), and into silico-argillaceous, or clayey 
soils, which do not contain carbonate of lime or of mag¬ 
nesia. Hence the agricultural principle is, in its turn, 
in agreement with the principle drawn from improve¬ 
ments, and no longer with that of tenacity; for in these 
two classes of lands, we find that, according to the pro¬ 
portion of the mineral principles which they contain the 
soils possess a different degree of tenacity. 
Other kinds of culture confirm this view. Fruit trees 
thrive admirably in siliceous and clayey lands, and these 
are generally the soils of forests; leguminous plants 
prefer soils in which there is a carbonate, and then they 
appear naturally; and it is only in the same circumstan¬ 
ces that dye-plants afford vivid colours. 
We have already remarked, that we cannot avail our¬ 
selves of the characters which are drawn from the te¬ 
nacity of the soil, without destroying the groups which 
we had previously formed. We can, however, reserve | 
them for the formation of secondary groups, which will 
subdivide the primary classes. It will be the same 
thing with those which are derived from the property 
which gypsum possesses of rendering certain soils emi¬ 
nently productive of vegetables; but we have seen that 
it is the geological position of soils, more than their 
Fourth Sub-Order, — Marls. 
Character. —After the action of acid, a clay remains 
whose levigation does not remove more than 0.10 of 
free silex. 
First Section.—Calcareous Marls. 
Character. —Having at least 0.50 of carbonate of lime 
or magnesia in their composition. 
Second Section.—Argillaceous Marls. 
Character. —Having at least 0.50 of clay. 
Fifth Sub-Order. — Loams. 
Character. —After the action of acid, the residuum pre¬ 
sents clay and free silica, which, by their levigation, give 
each more than 0.10 of the weight of the soil. 
SECOND DIVISION.— Soils with an Organic Base. 
Character. —Losing at least a fiftieth of their weight 
when they are heated till they do not emit more vapor. 
FIRST CLASS.— Fresh Mould. 
Character. —The water in which this mould is digest¬ 
ed or boiled does not redden litmus paper. 
SECOND CLASS.— Acid Mould. 
Character. —The water in which this mould is digest- 
led or boiled reddens litmus paper. 
I In each of these classes, the genera are formed by the 
| consideration of the tenacity of the soil, which is so very 
umportant an element in its characters. 
] The work concludes by laying down rules for the de¬ 
scription of species, and with examples of all the methods 
of description. In reading these, we at once perceive 
how precise an idea of soils is conveyed in a manner 
that cannot be misunderstood by any agriculturist.— 
The possibility of transmitting these clear and pointed 
descriptions to a distance, follows as a matter of course ; 
'and we shall in this manner be freed from all that vague¬ 
ness which has been so long a just cause of complaint. 
“If I have succeeded (concludes the author) in what 
I have proposed in writing this book, the study of agri¬ 
cultural treatises will be greatly facilitated; the diffe. 
rent methods which are followed in distant countries 
will no longer appear so marvellous, and will become 
more intelligible; we shall comprehend better the con- 
siderations which limit or extend the several cultures, 
and a necessary link being established between the sci¬ 
ence of agriculture and other natural sciences, it will 
become more intelligible to all, and will more readily 
.profit by the progress of all the other branches of hu¬ 
man knowledge.” _ 
about, before we calculate the expense of their produc¬ 
tion. 
As to improvements, and the necessary means of en¬ 
riching vegetation, they are without doubt the sign and 
consummation of good farming; but their use is much 
less frequent than it ought to be : most lands are culti¬ 
vated without their aid; and we cannot, therefore, con-; 
sider an exception which, we trust, will soon cease to] 
be one, in the light of a character so general as the pre¬ 
ceding. 
Upon the whole, therefore, we establish the subordi-i 
nation of the agricultural characters which ought to bel 
composition, which has hitherto contribted to designate 
them. But each of our groups contains earths of diffe¬ 
rent geological formations, so that we should run the 
risk of breaking them up if we were to introduce this 
consideration into the formation of our primary groups; 
and, upon the principle above insisted upon, this cha¬ 
racter will rank after the one derived from tenacity. 
These principles being allowed, we now proceed to 
the exposition of the classification of soils, which they 
supply. 
FIRST DIVISION.— Soils having a Mineral Basis. 
Character. —These soils do not lose a fourth of their 
weight upon heating them till they emit no more vapor. 
FIRST CLASS.— Saliferous Soils. 
Character. —Soils with a salt or styptic taste, contain¬ 
ing at least 0.005 parts of hydrochlorate of soda, or 
sulphate of iron. 
1st, Saline Soils. —Water digested with these soils, 
gives a precipitate with nitrate of silver. 
2d, Vitriolic Soils. —Hydrocyanate of potass gives a 
white precipitate with the ferruginous salt which is 
contained in the water digested with this soil. 
SECOND CLASS.— Siliceous Soils. 
Characters. —Producing no effervescence with acids ; 
affording by levigation at least 0.70 for their premier 
lot.* 
THIRD CLASS.— Clays. 
Characters. —Not yielding effervescence with acids, 
and affording by levigation less than 0.70 of the first 
portion 
FOURTH CLASS.— Calcareous and Magnesian Soils. 
Characters. —Producing effervescence with acids 
lime, or magnesia, or both, are found in the solution. 
First Sub-Order. — Chalks. 
Characters. —Leaving no residue after the action of| 
the acid, or only leaving a siliceous residue less than 
0.50. 
Second Sub-Order, — Sands. 
Character. —This soil contains at least 0.50 part of; 
siliceous or calcareous sand, which does not escape from 
a sieve whose division or holes are the 0.02 of an Eng¬ 
lish inch in diameter. 
Third Sub-Order.— Clays. 
Character .—This soil leaves a residue of 0.50 of clay 
after effervescence and levigation. _ 
* The 11 premier lot” comprehends the large particles] 
which are deposited when the water in which the earth is] 
dissolved, is strongly shaken. 
Upon the Respiration of Plants.* 
BY MESSRS. EDWARDS AND COLIN. 
In the interesting science of vegetable physiology few 
or no facts are to lie found more beautiful than those 
f connected with the respiration of plants. The same 
remark, however, can by no means be made concerning 
the theory which combines these facts, and undertakes 
to explain them. In fact, we have always experienced 
„ the greatest difficulty in admitting this theory, whether 
iy considered in relation to the respiration of the seed or 
of the leaves: and, in truth, scarcely any other pheno¬ 
menon has been recognized in the respiration of the seed 
than the disengagement of carbonic acid. This is usu¬ 
ally explained by the combination of the oxygen of the 
air with the carbon of the seed. According to this 
view, the seed is supposed to be affected only by the at¬ 
mosphere; the influence of water in this vital act of 
plants is considered either as absolutely nothing, or is 
limited to that of preparation and promotion, and it is 
held in no way to contribute to the production of the gas 
which is disengaged. This, then, is the first difficulty 
respecting this theory of germination which presents 
itself; and those which occur in regard to the explana¬ 
tion of the respiration of the leaves are still more seri¬ 
ous. During the night, it is said carbonic acid is disen- 
'gaged, whilst during the day it is absorbed, and oxygen 
'appears under the direct rays of the sun. Here, then, 
are the facts, and here the explanation which is afford¬ 
ed : the absorbed carbonic acid must be decomposed by 
the plant, which again must appropriate the carbon, 
and disengage the oxygen. 
But this capability of decomposing carbonic acid is 
conferring upon the plant a power which it is very dif¬ 
ficult to admit; and it is very seldom found in the mine¬ 
ral kingdom, where the very great simplicity of the com¬ 
position of bodies increases their decomposing power, 
and where the much greater number of elements, scat¬ 
tered throughout the different compounds of this king¬ 
dom, renders it probable that we should discover some 
endowed with this property. Finally, water, according 
to this supposition, is of little or no use in this action, 
although it is absolutely required for plants, and we are 
perfectly ignorant of the part it plays. These are some 
of the considerations which have induced us to under¬ 
take the examination of this function in plants; to which 
we were also conducted by some facts brought under 
our notice in agricultural physiology, to which we shall 
solicit attention in the sequel. 
Up to the present period, experiments upon the respi¬ 
ration of seeds have always been made in the air; or if 
made in water, the phenomena which occurred in the 
liquid have been limited to the explication of what took 
place in the air; the gas disengaged in the liquid has 
not been examined, and consequently its proportion has 
not been determined. What follows is an account of 
what we have done in relation to this point, and which 
has yielded very extraordinary results. Our operations 
were conducted on a great scale, that the effects of the 
experiments might be more distinctly brought out. 
* Read to the Academy of Sciences, Nov. 1838. From 
Annales des Sciences Naturelles, for December, 1838. 
