310 Proceedings of the Royal Society 
ether as a hydrate of olefiant gas. The result was one of those 
controversies which have proved of immense value in the progress 
of chemistry. In the course of this controversy the relations of 
alcohol and ether to other substances were investigated and dis- 
cussed with great minuteness, and the result was the general adop- 
tion of Liebig’s ethyl theory. The subject of decay, putrefaction, 
and fermentation early engaged Liebig’s attention. Entirely 
opposed to the vital theory of fermentation, he attacked it with 
both argument and ridicule, and proposed a purely chemical 
theory, which he defended with great ingenuity. 
A very important part of Liebig’s work in pure organic chemistry 
was carried on along with Wohler. As might be expected, the 
joint efforis of two men of such genius and industry produced 
results unexampled in number and importance. One of the first 
objects of their research (in 1830) was cyanic acid, a substance 
discovered by Wohler, and in which Liebig had a special interest 
from its isomerism with his fulminic acid. But the investigations 
undertaken by them, which exercised the greatest influence on 
the science of chemistry were those on the benzoic compounds and 
on uric acid. These are models of what such work ought to be, 
not only enriching the science with new facts, but compacting it 
by the discovery of new relations. The theoretical views brought 
forward in the papers on benzoic acid and bitter almond oil were 
the commencement of the development of the new theory of com- 
pound radicals which soon took the place of that of Berzelius. 
The most widely known part of Liebig’s work consists in his 
applications of chemistry to physiology and agriculture. The facts 
he discovered in reference to the chemistry of animal and vege- 
table nutrition, and the explanations he gave of the chemical pro- 
cesses involved in the life of organisms, have had an incalculable 
effect upon physiological chemistry. In his application of the 
principles of chemistry to agriculture, he proceeded in a thoroughly 
scientific manner; and although he in some cases generalised too 
fast, and was thus led into practical error, his work forms the foun- 
dation of a true science of agriculture. 
By far the greater part of Liebig’s scientific work was done at 
Gfiessen. After his removal to Munich, the claims of society and 
the court life of a capital upon his time made the devotion to 
