1209. Pulverisation increases the capillary attraction, or sponge-like property, of soils, by which their humidity is rendered more uniform. It is evident this capillary attraction must be greatest where the particles of the earth are finely divided; for gravels and sands hardly retain water at all, while clays, not open by pulverisation or other means, either do not absorb water, or when, by long action, it is absorbed, they retain too much. Water is not only necessary as such to the growth of plants, but it is essential as a kind of food, and as a medium through which plants absorb other food. Manure is useless to vegetation till it becomes soluble in water, and it would remain useless in a state of solution, if it so abounded as wholly to exclude air; for then the fibres or mouths, unable to perform their functions, would soon decay and rot off. Pulverisation, in a warm season, is of great advantage in admitting the nightly dews to the roots of plants.