Books on physics tell us that if a solid body is placed in contact with a fluid which is capable of moistening it, the fluid will mount up to a certain height on the surface of the solid body. If we immerse one end of a glass tube of small diameter in water, we shall find that the water will rise to a much greater height on the inside of the tube than on the outside of it. Experiment shows that the height water is capable of ascending inside a tube, varies inversely as the diameter of the tube. Thus, water will rise ten times higher in a tube of 1/100 inch in diameter, than in one of 1/10 inch diameter. This force, which has more power over water than over any other fluid, is termed capillary attraction. Some fluids, mercury for example, not only refuse to obey it, but even exhibit capillary repulsion. The smaller and more numerous are the tubes or interstices contained in a solid body, the more water will it be capable of absorbing; supposing that no chemical combination (as occurs with quicklime and water, for instance) takes place between the fluid and the solid. Hence, if we dip into water two sponges of the same size, but of different degrees of closeness of texture, we shall find after we have withdrawn them from the water and have allowed enough time to let all the extra moisture drain away, that the sponge which has the smaller interstices will have retained more water than the other.

As far as stable management is concerned, the subject of the absorption of fluids by solids applies chiefly to questions of bedding, stable construction, clothing and food.

Absorption Of Gases By Solids

"The surfaces of all solid bodies exert an attraction on the molecules of gases with which they are in contact, of such a nature that they become covered with a more or less thick layer of condensed gas" (Ganot). As a great rule, the absorbability of a solid for gases varies according to the extent of its external and internal surface. Consequently the more porous a body is, the greater power it usually has for absorbing gases. In almost all cases, the easier a gas can be liquefied by pressure, the greater capacity has it for being absorbed by solids. For instance, one volume of boxwood charcoal will absorb about 90 volumes of ammonia, 35 of carbonic acid, and 8 of air.