500 
Agricultural Chemistry. 
But it is time that some allusion should be made to the source- 
from which Mi\ Lawes's information is chiefly derived. It was 
about the time of the appearance of Baron Liebig's first work 
that Mr. Lawes commenced his scientific course of experiments 
on the application of special manures to various crops, and 
whether we look at the number of these experiments and the 
length of time over which they extend, or at the great skill, 
untiring labour, and unstinted expense bestowed upon them, or 
lastly, at the immense importance of the results obtained, we 
shall perceive that they are altogether unequalled in this or any 
other country, and that they entitle Mr. Lawes to the grateful 
thanks of his fellow-countrymen. 
What then are the main points at issue between the great 
chemist of Giessen and the great experimentalist of Rothamstcd ? 
In attempting a very brief answer, it must be premised that it is 
simply the impression left on the mind of an unscientific reader 
after a careful perusal of the rival statements. The leading fea- 
tures of the case then may be stated as follows : — Baron Liebig, in 
the first edition of his work on Agricultural Chemistry, points out 
the importance of the presence of vegetable and animal manures 
in the soil, in consequence of their furnisliing carbon and nitrogen 
to the growing plant in its early stages ; but in the later editions 
of that work, as well as in other publications, he treats the mineral 
ingredients of manure as of paramount importance, teaching that, 
if these latter are present in sufficient quantity and in available 
form, the requisite nitrogen and carbon will be obtained from 
atmospheric sources. The practical deduction to be drawn from 
these opinions is, that when endeavouring to increase the fertility 
of land, tlie first step to he taken is to employ a manure containing 
an ample supply of the mineral constituents oftlie crops to he groxon. 
The most satisfactory test that can be obtained of any man's 
opinions is that furnished by his own practical application of 
them ; and had any doubt existed as to the correctness of the 
foregoing brief statement of Baron Liebig's doctrine on this point, 
it would have been removed by the fact, that when a manure for 
wheat was brought out in this country under the name of Liebig's 
manure, the composition of which, there is every reason to be- 
lieve, received his direct sanction, it consisted of the mineral con- 
stituents of the wheat crop. 
On the other hand, Mr. Lawes's experiments soon convinced 
him that an artificial supply of nitrogen in the soil was generally 
necessary when an increased growth of corn was desired. His 
first paper on this subject appeared in this Journal in 1847, and 
the very plain indications afforded by the experiments there re- 
corded were strongly confirmed by numerous additional facts 
contained in the article published in 1851, also in this Journal, 
