THE CULTIVATOR. 
36‘ 
not doubt; the whole body seemed quite unanimous in 
expressions of approbation. 
We were mentioned by Mr. Milne as rivals in the in¬ 
troduction of this new branch of education, and I trust 
’hat we shall prove formidable rivals, that our rising 
generation will take the field so armed with the true 
principles of cultivation that in 20 years from this time 
we shall no longer need to look to Scotland as a model. 
The Scotch would call this American conceit, but they 
don’t know what we can do when we are in earnest. 
Very truly yours, John Pitkin Norton. 
ON ARTIFICAL MANURES. 
BY PROF. JUSTUS LIEBIG. 
[Our friend and correspondent at Giessen, Prof. Hors- 
ford, has sent us the following copy of a communication, 
written by Dr. Justus Liebig for the first No. of the 
« Agricultural Magazine,” a work recently commenc¬ 
ed in London, and for which the copy-right was secured 
in England.] 
Sir —Twenty-five years ago, when the manufacture of 
spa and mineral waters began, they met with violent op¬ 
position from the members of the faculty, as being de¬ 
prived of all the good qualities of the natural ones—as 
wanting in a certain conditio sine qua non —in a spiritus 
rector, or vital power, which alone gave them any medi¬ 
cinal qualities. Those times have passed now—Chemis¬ 
try has demonstrated to a certainty what the constituents 
of those various waters are, and under what forms and 
compounds they are united in them. It has succeeded in 
combining them exactly in the same proportions, and in 
rendering them not only equal to the natural ones, but 
even more effective. Only from that time physicians 
were induced to connect certain effects on the human 
body with certain elements in the waters, and were ena¬ 
bled, by the light of science, to add more of this ele¬ 
ment, or more of that; nay, to apply, instead of the wa¬ 
ters themselves, the one active element alone, as is, for 
instance, the case with Iodine in indurations and struma. 
It is well known, that at this moment there are exten¬ 
sive manufactures of mineral waters in England, in Ber¬ 
lin, in Dresden, in Vienna, &c. 
Now, T believe, sir, that the same principle may be 
applied, partially, at least, totheuse of manufactured ma¬ 
nures, which, in England, has just been called into exist¬ 
ence. Guano, that powerful manure, the efficacy of 
which, in a judicious application, has been clearly de¬ 
monstrated by the testimony of the most intelligent far¬ 
mers, cannot be supplied for a much longer period to 
come. The rich stores in Chili and Africa must be 
shortly exhausted. As it is only in very dry countries 
that it is found, we cannot expect to discover many more 
places containing it, and what are we then to do? My 
attention has often been directed to the question, whether, 
according to our experience, and the present slate of 
science, a manure might not be composed which could 
replace the genuine Guano in its effects, and whether I 
could not, by a series of experiments point out a way of 
preparing one equal to it in all its chemical and physical 
properties? You are well aware, sir, that we know with 
certainty all the elements of the guano, as well as of the 
urine and solid faeces of men and animals. In like man¬ 
ner it seems to have verified the opinion which I have 
laid down in my work on Agriculture, that the salts 
manufactured in the laboratory have the same effect on 
the growth of the plants, if they are embodied to the 
fields, in the same forms in which the animals fur 
nish them in their excrements. This must be evi¬ 
dent to every one who knows, that to produce these 
compounds in the laboratory, the same agencies and 
means are made use of which are employed by nature. 
The fabrication of a manure, equal in its composition 
and effects to the solid anil fluid excrements of animals 
and men, seems to me one of the most essential demands 
of our time—more especially for a country like England 
in which from various circumstances, a rational agricul¬ 
ture without a supply of manure in some shape or other, 
from without, seems nearly impossible. Our reasoning 
will appear the more correct, if we remember how dif¬ 
ferent are the results which have been obtained by the 
numerous analyses of the different sorts of guano—how 
little the farmer can depend upon producing from a given 
quantity a certain effect, as the latter naturally varies accor¬ 
ding to the composition of the former. There are scarce¬ 
ly any two samples in the market with the same compo¬ 
sition—nay, not even similar. The following may be 
regarded as the essential constituents of a powerful ma¬ 
nure applicable to all sorts of soils:— 
Earthy Phosphates. —The most important of these is 
Phosphate of Lime, which occurs in nature as a mineral 
called apatite. It is the principal element in the bones, 
which, it may be observed, have been found most effi¬ 
cacious if calcined, consequently deprived of their ani¬ 
mal matter. The rapidity of the effects of phoshate of 
lime on the growth of plants depends upon its greater or 
lesser solubility. Its amount of glue (gelatine) diminish¬ 
es this solubility if the soil is rich in vegetable matters, 
which furnish carbonic acid by their decomposition, and 
which acid is required for rendering the phosphate of lime 
soluble in water and introducing it into the organism of 
the plants. In the calcined state the bones act sufficient¬ 
ly quickly; but in those soils in which thiscause of solu¬ 
bility is wanting, theiraction is slower. In my work 1 had 
recommended the addition of a certain quantity of sul¬ 
phuric acid, both in order to render the bones more solu¬ 
ble and to change the neutral phosphate of the bones into 
gypsum, and into a phosphate which contains more acid 
(superphosphate of lime.) I have been informed that 
this advice has been most extensively adopted, that the 
superphosphate of lime has been found to be a most effi¬ 
cacious manure, and that it forms already a most import¬ 
ant article of commerce. A second earthy phosphate, 
not less important, is the Phosphate of Magnesia, which 
it is well known enters in a still larger proportion than 
the phosphate of lime into the composition of the grain. 
The Alkaline Phosphates, although not originally found 
in nature, are important elements of the seeds of grain, 
of peas, beans, &c. A rational farmer must provide 
them in sufficient quantities to those plants -which re¬ 
quire them for their development, from knowing that 
human excrements increase the produce in grain in a far 
greater proportion because they contain alkaline phos¬ 
phates, than the animal excrements, in which they do not 
exist. 
The Alkalies (potash and soda) must be constituents of 
every rationally composed manure, because by them the 
original fertile condition of the fields is preserved. A 
soil which contains the alkalies in too small a quantity, is 
perhaps, fertile for grain; but is not necessarily so for 
turneps or potatoes, which require a great quantity of 
jalkali. By supplying an alkaline manure, fallows, or 
|the cultivation of those plants which are grown during 
the time of fallowing, becomes less necessary. 
Sulphate of Potash is a constituent of ail plants, al¬ 
though in small quantity, as well as common salt and chlo¬ 
ride of Potassium which are found in milk in rather a large 
proportion. The salts of lime, especially gypsum, are 
important nourishment for the leguminous plants. Silica 
is never wanting in all sorts of soils—it is a constituent 
of all rocks, by the decomposition of which all product¬ 
ive soils are formed, and the cerealia find it every where 
in sufficient quantity, and in a form capable of being 
taken up by the plants, if the alkalies are provided 
wherever they are present in too small quantity. 
Salts of Ammonia. —It can be regarded ascertain, that 
the azote of the plants is derived, either from the ammo¬ 
nia of the atmosphere, or from the manure which is pro¬ 
vided in the shape of animal fluid and solid excrements, 
and that azotic compounds exercise an effect on the 
growth of plants, only in so far as they give up their 
azote in the form of ammonia during their decomposi¬ 
tion and decay. We may, therefore, profitably replace 
all the azotic substances with compounds of ammonia. 
Decaying vegetable matters, which contain carbon, are 
juseful to the fields in so far as they provide a source of 
carbonic acid; but they are not quite indispensable inma 
[nure, if the latter be rationally combined, as the atmos 
ipheric ah* is an inexhaustible source of carbonic acid 
