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 absorbed by an acre of land in a dry season, by considering that the clay loam, in the above statement, absorbed in 12 hours a fortieth part of its own weight. OF DEW. Dew is one of the most ordinary forms in which moisture is deposited in and upon the soil, in its natural conditions. The absorbent power of artificially-dried soils, as has been seen, seems to depend much upon their chemical constitution; and that topic has been considered, without special reference to the comparative temperature of the soil and atmosphere. The soil, as we have seen, absorbs moisture from the air, when both are of the same temperature, the amount absorbed depending also upon the physical condition of the soil, and upon the comparative moisture of the soil and atmosphere.