486 
Agricidtural Clicniistry. 
Wolff has to a great extent adopted this view ; and has adduced 
various circumstances connected with the development of these 
plants, as corroborative of its probability. Baron Liebig has, on 
the other hand, eners:etically repudiated the explanation offered 
by Mr. Way ; founding his objections on the fact, that water 
containing ammonia or its salts dissolves less of the alkaline 
silicates than does pure water itself. Experiments of this kind, 
made upon chemic al compounds out of the soil, cannot be con- 
sidered satisfactory as the ground of conclusions as to what 
would happen under the complicated conditions of cultivated 
soils. We have, however, found, that water containing salts of 
ammonia dissolved less silica than pure water, when percolated 
through a given bulk of soil. But the question may, after all, 
not so much depend upon the amount of the silica which will be 
dissolved in the soil, as upon the state of chemical combination 
from which it is most easily assimilated by the plant. 
It has been with a view to aid the solution of the question of 
the varying amount and sources of the nitrogen assimilated by 
the different plants of our rotations, that we have, for a series of 
years, conducted investigations on the amount of water passing 
through different plants, under equal and varied conditions of 
growth, in relation to the quantitative fixation in them of 
their several constituents. The results of these investigations, 
as we have elsewhere pointed out, have an interesting bearing 
upon the phenomena we have been discussing. But so important 
has it appeared to us, to clear up many open questions which 
suggest tiiemselves, that not long ago we induced a promising 
and accomplished young cliemist from the laboratory of Professor 
Bunsen (Dr. August Pauli), to devote himself for two years to 
this subject, in the laboratory at Rothamsted. Unfortunately, his 
death, almost as soon as he had commenced his labours, pre- 
vented the further prosecution of the exact path of research then 
proposed ; though we still hope that investigations which we 
have for some time had in progress, and to which we shall now 
direct more close attention, will enable us to record before long, 
further advance in our inquiry. 
But there are means adopted by the farmer of increasing 
the growth of grain, without either the artificial supply of 
nitrogen to the soil, or the intervention of a fallow crop. These 
are, hare fallow and the mechanical operations of the farm. Now, 
as Baron Liebig has modified his views on the efficiency of these 
means, in his ' Principles ' just published, we must take the 
statement of his views as given in the tliird and fourth editions 
of his main work, to show what were the views which, until 
lately, he advocated on this question. In these editions he gave 
a distinct and separate chapter on fallow and the mechanical 
