106 
Oit the Chemical Properties of Soils. 
These impressions, though natural, are not founded on fact. 
It will be one of the objects of this communication to show by 
many experiments the fallacy upon which these erroneous impres- 
sions are based. 
If soluble fertilizing matters were rendered completely insoluble 
when brought into contact with the soil, it would indeed be 
difficult to understand the use of soluble manuring matters, or to 
doubt the policy of resorting to mechanical means of cultivation, 
such as subsoiling, stirring, &c., which have the effect of render- 
ing soluble mineral matters contained in the soil in an insoluble 
state. But does not daily experience teach us that such fertilizers 
are much more effective than the same materials in an insoluble 
or partially soluble condition ? 
It has indeed been stated by a high authority, that since soluble 
fertilizing matters are rendered insoluble in contact with soil, 
plants must have the power of taking up their food fi'om the soil 
in some other form than that of simple solution. It is here taken 
for granted that soluble matters become quite insoluble in contact 
with soil. Many people, on being told that plants do not take 
up their food from the soil in the state of simple solution, assume 
that they take it up in a solid form. . 
It is not my intention to expound in this place Baron Liebig's 
views on the assimilation of the food derived by plants from the 
soil. The changes which fertilizing matters undergo in contact with 
soil are, as we know, so numerous and so little understood, and the 
precise combinations in which mineral food is taken up by plants 
so little known, that it would be extremely hazardous to propound 
in detail a new theory respecting the assimilation of mineral 
food by plants. Baron Liebig, therefore, wisely refrained from 
expressing his views on this subject in that clear and precise 
manner which generally distinguishes his writings, and very pro- 
perly contented himself with indicating that our present views 
respecting the absorption of mineral matters by plants are not 
quite correct. 
Professor Way's and my own researches certainly have shown 
that manuring matters in contact with soil undergo remarkable 
changes, and fully justify the statement that plants do not take 
up mineral food in the simple state of solution in which we add 
it to the soil in the shape of manure, but in totally different 
states of combination. 
Again, if sandy soils had not the power of retaining spluble 
fertilizing matters, it would be difhcult to cc^mprehend how, not- 
^withstanding the occurrence of heavy thunderstorms or long- 
. continuing rains, the effects of superphosphate or guano, or even 
:sulphate of ammonia, are clearly seen in the increased produce 
raised on such soils by the aid of these manures. 
