e thirsty soil, and bringing
within the reach of plants, a portion of the moisture, which,
during the day, they had so copiously exhaled."

Different soils possess this power in unequal degrees. During a night of
12 hours, and when the air is moist, according to Schuebler, 1000 lbs. of
perfectly dry

Quartz sand will gain 0 lbs.
Calcareous sand 2 "
Loamy soil 21 "
Clay loam 25 "
Pure agricultural clay 27 "

Sir Humphrey Davy found, that the power of attraction for water,
generally proved an index to the agricultural value of soils. It is,
however, but one means of judging of their value. Peaty soils and strong
clays are very absorbent of water, although not always the best for
cultivation.

Sir H. Davy gives the following results of his experiments. When made
perfectly dry, 1000 lbs. of a

Very fertile soil from East Lothian, gained in an hour 18 lbs.
Very fertile soil from Somersetshire 16 "
Soil, worth 45s., (rent) from Essex 13 "
Sandy soil, worth 28s., from Essex 11 "
Coarse sand, worth 15s. 8 "
Soil of Bagshot Heath 3 "

"This sort of attraction, however," suggests a writer in the
Cyclopedia of Agriculture, "it may be believed, depends upon other
causes besides the attraction of adhesion. The power of attraction,
which certain substances exhibit for the _vapor_ of water, is more
akin to the force which enables certain porous bodies to absorb and
retain many times their volume of the different gases; as charcoal,
of ammonia, of which it is said to absorb ninety times its own
bulk."

Here again, we find in the soil, an inexplicable but beneficent power,
by which it supplies itself with moisture when it most needs it.

Warm air is capable of holding more vapor than cooler air, and the very
heat of Summer supplies it with moisture by evaporation from land and
water. As the air is cooled, at nightfall, it must somewhere deposit the
water, which the hand of the Unseen presses out of it by condensation.

The sun-dried surface of fertile, well drained soil, is in precisely the
condition best adapted to receive the refreshing draught, and convey it
to the thirsting plants.

We may form some estimate of the vast amount abs