ORGANIC CONSTITUENTS OF SOIL. 
Dana’s Mack Manual is one of the most 
uselul works for the farmer ever published. — 
The reader who will peruse diligently the ex- 
tract below will be amply rewarded tor his la- 
bor. — American Farmer. 
ON THE ORGANIC CONSTITUENTS OF SOIL. 
The mineral elements of soil, become part of 
plants. Under the influence of the mysterious 
principle ol lile, they no longer obey the chem- 
ical laws. It organizes inorganic matter. To 
what laws obedient, to what purposes subservi- 
ent, are the elements of soil during the briei 
moment in which they are endowed with life, it 
is not intended to inquire. Plants by their liv- 
ing power select from the 55 elementary sub- 
stances fllteen only; of these, three are gaseous, 
o.xygen, hydrogen, nitrogen; one, chlorine, ex- 
ists only as a component of a salt, as in com- 
mon salt; seven belong to the class silicates, 
second division, and four to the class urets. 
Every plant does not, nor does every part of 
the same plant contain the same elements; but 
every part of the same plant at the same age, 
probably contains the same elements, united in 
definite proportions. Whenever plants die, 
their elements are again subject to the laws of 
affinity, and during the decay of vegetables, 
they return to the earth, not only those substan- 
ces which the plants had taken from the soil, but 
also those which have been elaborated by their 
living structure. The former are silicates and 
salts, or the inorganic elements, the latter are 
the organic parts of soil. 
In the first edition of this work, chlorine was 
not enumerated as an element ol plants. Its 
presence in them was considered accidental, be- 
cause its source was not detected in the rocks, 
from whose ruins soil has beeu lormed. Plants 
are good analysts, and may detect elements 
where chemi.stry cannot; yet it is difficult to be- 
lieve that chloride can exist as abundantly in 
soil, originally, as their presence in plants indi- 
cates, and yet elude our process. The possible 
e.xistence of chloride of silican has been notic- 
ed. If this is not the source of the chlorine of 
plants, it must be supposed to be evaporated as 
a chloride from the ocean, and consequently to 
exist in that state, dissolved in air. If derived 
Irom this salt in soil, then that is extraneous. — 
Its origin was suggested to be oceanic. An ex- 
amination of the rain-water of each fall, since 
March last, has shown that this suggestion is 
correct. Probably muriates are universally 
contained in rain-water. As, therefore, com- 
mon salt, the chlorine, and soda of plants, is 
derived by evaporation from sea water, then as 
sulphate of lime has been delected in snow and 
hail, it becomes a question, whether other inor- 
ganic salts of plants may not have a similar or- 
igin, and exist dissolved in air. 
It is thu.s seen that soil presents itself in a new 
view. Soil consists of two grand divisions of 
eleruents. Inorganic and organic. The inor- 
ganic are wholly mineral, they are the products 
of the chemical action of the metalic, or unme- 
talic elements of rocks. They existed before 
plants or animals. Life has not called them 
into existence, nor created them out of simple 
elements. Organic elements are the product of 
substances one# endowed with life. This pow- 
er influences the elements, recombines them in 
forms, so essentially connected with life, that 
they are, with few exceptions, produced by a 
living proce.ss. They are produced of living 
organs, hence term.ed organic: and when form- 
ed are subject to chemical laws. The number 
of elements in the inorganic parts of soil, is 
twelv'e. Oxygen, sulphur, phosphorus, carbon, 
silicon, and the metals, potassium, sodium, al- 
umniuai, rnagnisium, iron, and magnese. The 
number of elements in organic parts of soil, 
does not exceed four, oxygen, hydrogen, car- 
bon, and nitrogen. 
The great difference between these two divi- 
sions is this, that while the inorganic are sim- 
ple combinations of two elementary substances, 
the organic are combinations of three or four 
elements, but never less than three. These are 
variously combined. They have formed the 
great body of vegetable products; continually 
changing, the mere abstraction of a part of one 
of their elements forms a new product. The 
three elements exist generally in such propor- 
tion, that the o.xygen and h3’drogen would, bv 
their union, produce water without excess of 
either element, while the carbon would thus be 
liberated. It would be found Iree were it not 
also acted upon by air and moisture, and chang- 
ed to carbonic acid. There is not oxygen enough 
in the organic part to convert the carbon into 
carbonic acid, and the hydrogen into water. — 
They are con-stamly changing, assuming new 
forms. This susceptibility of change is the 
foundation of tillage. 
The relation of agriculture to silicates and 
salts, and to the composition of plants alluded 
to, (89.) is of the highest interest. As silicates 
and salts compose all the earthy ingredients of 
soil, so aretheyequaily constant in plant.-^. The 
deduction to be drawn from this, is the sixth 
principle of agricultural chemi.stiy, soil, consist- 
hig chiejly oj one silica, or salt, is oltcai/s barren. 
It is not probable that soil, thus chemically 
constituted, exists. Admitting such to occur, 
even then, when dres.scd with food of plants, it 
would not be fertile. The want of a mixture of 
earthy ingredients, which are as essential to the 
growth ot plants as are air and moisture, would 
effectually prevent the gr owth of crops. Only 
a portion of the elements, thus essential to plants, 
exists in them in that .state in which they exist 
in soil. The silica, and potash and lime, exists 
in plants as in soil, as silicate of pota.sh, and 
sulpliates and phosphates of lime and potash. 
When the ashes of plants are examined, we 
find carbonate of bases, which did not exist as 
such in the soil. A large portion of carbonates 
of lime and potash is found in ashes. 
The origin of these is to be sought in acids, 
which, by heat, produce carbonic acid. This is 
the effect of heat upon all salts formed of vege- 
table acids. Such as tartaric, malic, citric, ox- 
alic and acetic acids. The inorganic elements 
of plants exist i i combination chiefly with or- 
ganic or vegetable acids. Each plant forms 
acids, in definite quantit}'’, proportionate to the 
size, age and part of the plants;; the acid being 
con.'tant, the bases to saturate them will be 
equally constant. 
A curious and beautiful chemical law governs 
this satuaration of the vegetable acids. It is 
the law of isomorphism, or the law of similar 
forms. In minerals which are crystalized, it 
was formerly thought that similarity of eternal 
form, indicated identity of chemical composi- 
tion. Later observation has established the 
fact that minerals and salts exist, with perfect 
similarity of external form, yet of totally dif- 
ferent chemical constitution. For example, the 
alumina in alum, may be replaced by oxide of 
iron. The lorm will not be changed; but all ils 
chemical properties and relations are destroyed. 
This is callud an isomorphous substitution, of 
one element for another, which produces a like 
form. The Law of this substitution is, that the 
body replacing another mu.st be, not an equal, 
but an equivalent proportion (50;) that is, re- 
placed by a proportion containing the same 
quantity of oxygen. 
The relation between agriculture and this 
law is .':o wisely and beneficially ordained, that 
it might well be called a lavv ol compensation, 
by the Natural Theologian. It is a well estab- 
lished fact, that plants, growing on soil contain- 
ing a due mixture ol'earthy ingredients, always 
select a due proportion of each, according to 
their functions, yet, if to such soil an excess of 
either of the alkalies, or of the alkaline earths 
is given, an excess of potash, soda, lime, mag- 
nesia, may be taken up by the plants, to the ex- 
clusion of the usual proportion of another; 
hence it may be established as the seventh prin- 
ciple in Agricultural Chcinislr}', one base may 
be substituted for another, in an isomorphous 
proportion. 
This is a very important law in the agricul- 
tural relations of the inorganic parts of soil. — 
Whatever may be the office performed by these, 
in the living structure, none is of higher value 
than this, that they may be thus substituted, the 
one for the ether. It is a fact of the highest 
practical value. Its value will be perceived, 
when it is considered, that if soil, containg ori- 
ginally all the elements essential to a crop, be- 
comes exhau.‘?ted of one, yet another may be 
substituted, which combining with the organic 
acid of the plant, enables this to perform and 
perfect all its functions. If a crop fails, this is 
often charged upon the deficiency of lime in the 
soil. It has been already shown that this i.s 
quite impossible, yet granting it true, so long as 
the law of isomorphi.sm exists, so long may 
potash, soda, magnesia, that is, ashes, supply 
the place of lime. 
Isomorphous .substitutions in plants, relate 
only to the bases combined with the vegetable 
or organic acids. The mineral or inorganic 
acids exist already saturated in the soil, as sul- 
phates, phosphates, or muriates. 
In consequence of the law of isomorphism, 
the oxygen is the bases of organic acid salts is 
a ccn.stant quantity, although ashes of the same 
plant may, by analysis, show a great diversity 
of composition; this can arise only from the 
fact that the organic acids exi.'t, probably in a 
definite proportion in each family' of plants. — 
The acids are formed by the essential vita! 
functions of the plant. To the perfection of 
this proce.ss, the silicates amd salts ol the soil 
are not less necessaiy than is life to the vegeta- 
ble; but though one element may be substituted 
for another, yet no one element may supply the 
place of all others. This is a problem yet to 
be soh'ed. Nor may' any possible mixture of 
mere silii'ates and salt? give fertility to a barren 
soil. Fertility depends on the presence in soil 
of matter which has already formed a part of a 
living structure, or the organic eiement.s of soil. 
The inorganic are simple combinations; the 
organic simple in number, but wonderful com- 
plex in their combinations. It is an establish- 
