matter in the soil? My idea is that it does both, and
that carbon in the soil does good if it offers an abundant supply
of carbonic acid to the plant when it is in a condition to
appropriate it. Your allowance of lime appears to me to be far
too small, for if any reliance can be placed on my experiments,
lime can be profitably used to far greater extent than you seem
to imagine. And, again, you seem to think that where there is
plenty of silex in the soil, the plant will be able to obtain as
much as it requires. I think that it is quite necessary that the
silex should be in a soluble state, as I think that it is not
only desirable that all the elements necessary to fertility should
be in the soil, but that they should be in such a form that they
can be assimilated by the plant. Some of our compounds for
producing fertility may perhaps be as absurd as it would be to
give muriatic acid to a man troubled with indigestion, because
free muriatic acid is found in the stomach of a healthy person.
Let me recommend you to try both silex and magnesia in a soluble
state, and I think you will be satisfied with the benefit derived
from their use.

Recurring again to the quantity of manure necessary to grow
thirty-six bushels of wheat, I would ask, why limit yourself to so
small a crop? The difference in the cost of your manuring a field,
and my manuring it, is more than made up by the increase of
fourteen bushels of wheat and the corresponding increase of straw,
even if the land did not improve every year by the application;
and as the seed, rent, labour, and liabilities of the land are the
same whether you grow a small crop or a large one, why not have it
as large as possible? Again, if I applied far more manure than was
necessary, I ought to have had the crop equally good throughout
the field; but on the ridge of the hill, where the soil was thin
and poor, neither straw nor wheat were so good as they were where
it was deeper and richer. My own opinion is, that the plant is
never able to extract from the soil all the manure, and therefore
it ought to be brought up to a good standard before good crops can
be expected. I am not satisfied with any analogy that I can think
of, but the best that occurs to me is that of a cloth in a dye-
copper. You can never get it to absorb either all or half the
colouring matter, and if you don't use far more than is taken up
by the cloth, you will never obtain the desired results. Besides,
in c