re the power of retaining water, and keep that
water ever charged with carbonic acid: thus not only the extraneous
manures which the farmer applies are fully economized; but the soil
becomes more productive from its own stores of fertility which now begin
to be unlocked and available.

Dr. Peters, of Saxony, has made some instructive experiments that are
here in point. He filled several large glass jars, (2-1/2 feet high and
5-1/2 inches wide) with a rather poor loamy sand, containing
considerable humus, and planted in each one, June 14, 1857, an equal
number of seeds of oats and peas. Jar No. 2 had daily passed into it
through a tube, adapted to the bottom, about 3-1/4 pints of common air.
No. 3 received daily the same bulk of a mixture of air and carbonic acid
gas, of which the latter amounted to one-fourth. No. 1 remained without
any treatment of this kind, _i. e._: in just the condition of the soil
in an open field, having no air in its pores, save that penetrating it
from the atmosphere. On October 3, the plants were removed from the
soil, and after drying at the boiling point of water, were weighed. The
crops from the pots into which air and carbonic acid were daily forced,
were about _twice as heavy_ as No. 1, which remained in the ordinary
condition.

Examination of the soil further demonstrated, that in the last two
soils, a considerably greater quantity of mineral and organic matters
had become soluble in water, than in the soil that was not artificially
aerated. The actual results are given in the table below in grammes, and
refer to 6000 grammes of soil in each case:--

ACTION OF CARBONIC ACID ON THE SOIL.
-----------------------------------+-----------+--------+------------
| _No. 1, | |
| Without |_No. 2, | _No. 3,
_Substances soluble in water, etc._| Artificial| Common | Air and
| Supply of | Air | Carbonic
| Air._ | Added._|acid added._
-----------------------------------+-----------+--------+------------
Mineral matters | 2.04 | 3.71 | 4.99
Potash | 0.07 | 0.17 | 0.14
Soda | 0.17 | 0.23 | 0.28
Organic matters | 2.76 | 4.32 | 2.43
| | |
Weight