PRESERVATION AND APPLICATION OF MANURES. 
251 
vegetable mould, without the presence of matter 
containing nitrogen.”—p. 126. 
Before the time of Liebig, it was a matter of great 
doubt, whence the nitrogen was derived, which was 
found in the composition of plants, and without 
which they could not attain maturity. To him we 
are indebted for the discovery, that this essential 
food of plants is derived from ammonia,* a gaseous 
substance contained in the atmosphere, and being 
extremely soluble in water—p. 130—is brought 
down to the earth by dews, rain, and snow,'and 
thus furnishes growing plants with nitrogen, an 
ingredient indispensably necessary to their ex¬ 
istence. Ammonia has a powerful affinity for 
water; consequently that portion of it, which is 
not taken up by the roots of plants, is liable to be 
carried off by evaporation, unless the soil contains , 
or is furnished with, substances capable of convert¬ 
ing it into a salt, and thus fixing it in the soil. 
Liebig has entered into some nice calculations to 
show what quantity of ammonia is given to the 
soil by rains, dews, and snows, annual'llj —p. 131; 
but is of opinion that the quantity, though great, 
is not sufficient for the purposes of agriculture—p. 
141, ami hence the necessity for an additional sup¬ 
ply, which I will hereafter show may be supplied 
by stable and other manures of the solid and liquid 
kind. As the nitrogen 'furnished by ammonia is 
so essential to the growth of plants, and as the 
quantity thus obtained is not a full supply, and a 
part of it is, moreover, liable to be carried off by 
evaporation, it is of the utmost importance to agri¬ 
culturists to use the most efficient means of fixing it 
in the soil, as it is brought down by rains, dews, 
and snows. 
This may be completely effected by strewing a 
small quantity of gypsum upon the soil, which, 
combining with ammonia forms soluble sulphate of 
ammonia and carbonate of lime, which, possessing 
no volatility, is retained in the soil—p. 142. 
Gypsum is very slightly soluble in water, and 
is very slowly decomposed by carbonates, and 
hence it may continue in the soil for several years 
—p. 144. 
Powdered charcoal acts in a similar manner, and 
has a powerful tendency in fixing ammonia in a 
soil—-p. 146. Decayed wood has also a similar 
tendency, and is almost as powerful as charcoal — 
p. 146. 
Each of these substances may be resorted to for 
fixing in the soil the ammonia derived from the 
atmosphere, but undoubtedly ground gypsum (sul¬ 
phate of lime) is the best adapted to the purpose, 
and ought to be resorted to, if to be obtained upon 
reasonable terms. 
it is proper to remark that some soils have 
already a due proportion of gypsum combined with 
them; and in that case no additional supply will 
be needed. This can be best ascertained by 
analyzing the soil. 
Before l proceed to speak of stable and other 
manures, in the solid and liquid form, I must take 
some notice of the inorganic manures, that is, of 
those substances which are found in the ashes of 
plants. 
* Ammonia is a compound gas, consisting of one 
volume of nitrogen, and threp 
Upon the incineration of every species of plants 
there are found, in the ashes, certain inorganic 
substances of such a fixed nature, that they cannot 
by any degree of heat be made to assume the 
gaseous state. Among these are the alkalies, and 
the alkaline earths, phosphates, silica, manganese, 
oxides of iron, &c., and various acids, combined 
with alkalies, and alkaline earths, &c. All these 
inorganic substances are not found in every species 
of plants; but that they are essential to the growth 
of plants, in whose ashes they are found, is an ir¬ 
resistible inference from the fact, that they are 
invariably found in such ashes, with this exception, 
that one alkali or alkaline earth may be substituted 
for another. Thus, if a plant, in whose ashes 
soda is usually found, should be planted in a soil 
where there is potash, but no soda, upon incinera¬ 
tion there will be found the alkali potash, which 
has thus been substituted for the alkali soda, and 
so vice versa. And if there should be neither soda 
nor potash, in the soil, these plants, whose appro¬ 
priate food is soda or potash, would substitute one 
or more of the alkaline earths in its stead—p. 200. 
And the acids combined with these alkalies, are 
always in proportion to their bases, so that the 
quantity of the one always regulates the other —pp. 
148-9-50. 
Nothing can more strongly show the absolute 
necessity of alkalies, or alkaline earths of one 
kind or another in plants. For if they are so situ¬ 
ated as not to be able to procure a supply of their 
appropriate alkali, they invariably supply them¬ 
selves with another, or even with an alkaline earth 
as a substitute. But one or the other they must 
have. Certain inorganic acids are also essential to 
the growth of plants, but these are always found 
combined with their bases, and in suitable quantity. 
Phosphoric acid has been found in the ashes of all 
plants hitherto examined, and always in combina¬ 
tion with alkalies, or alkaline earth—p. 200. 
Among the inorganic substances, the alkalies are 
the most important. They are found in different 
plants in the form of silicates, tartrates, citrates, 
acetates, oxalates, &c.—pp. 214-15. So important, 
in the opinion of Liebig, are alkalies in a soil, that 
even those which are the richest in humus must 
become barren and unfruitful when their alkalies 
are exhausted, and will remain so until they shall 
again be supplied with a due proportion of these 
indispensable ingredients—p. 196. Some of the 
inorganic substances exist in such great abundance 
that there is no danger of there ever being a 
deficiency in the soil. Among these is silica—p. 
215 (note), an ingredient which is essential to all 
plants of the grass kind—p. 200; and to all the 
grain tribe. The inorganic acids, or such as com¬ 
bine with inorganic bases, also exist in great 
abundance, so much so that wherever the base is 
found, it is accompanied by its due proportion of 
acid. Liebig says the most important object of 
agriculture is to furnish the soil with nitrogen , “ in 
a form capable of assimilation”—pp. 233-4. He 
might have added that it is equally important 
where alkalies are deficient, or when they have 
been exhausted, that they should also be supplied 
It has been seen, that of the organic manures the 
only one not furnished, in adequate quantity, by 
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