rrived at.

_Improving the Soil by Paring and Burning._--It has long been familiarly
known, that a decided improvement has been produced on some soils by
burning. Its advantages have chiefly been observed on two sorts, heavy
clays and peat soils, on both of which it has been practised to a great
extent. The action of heat on the heavy clays appears to be of a twofold
character, depending partly on the change effected in its physical
properties, and partly on a chemical decomposition produced by the heat.
The operation of burning is effected by mixing the clay with brushwood
and vegetable refuse, and allowing it to smoulder in small heaps for
some time. It is a process of some nicety, and its success is greatly
dependent on the care which has been taken to keep the temperature as
low as possible during the whole course of the burning.

Experience has shown that burning is by no means equally advantageous to
all clays, but is most beneficial on those containing a considerable
quantity of calcareous matter, and of silicates of potash. In such clays
heat operates by causing the lime to decompose the alkaline silicates,
and liberate a quantity of the potash which was previously in an
unavailable state. Its effect may be best illustrated by the following
analyses by Dr. Voelcker of a soil, and the red ash produced in burning
it.

Soil. Red Ash.
Water 0.93 1.18
Organic matter 10.67 3.32
Oxides of iron and alumina 13.40 18.42
Carbonate of lime 23.90 8.83
Sulphate of lime trace 1.15
Carbonate of magnesia 1.10 "
Magnesia " 1.76
Phosphoric acid trace 0.71
Potash 0.38 1.08
Soda 0.13 "
Chloride of sodium " 1.03
Insoluble matter, chiefly clay 49.66 62.52
----- -----
100.17 100.00

In this instance the quantity of burned soil amounted to about fifteen
tons per acre, and it is obvious that the quantity of potash which had
been liberated from the insoluble clay and the phosphoric acid are equal
to that contained in a considerable manuring. In order to obtain these
results, it is necessary, as has been already observed, to keep the
temperature as low a