Absorption.

Absorption. In Physics, when a quantity of matter or of energy enters into a substance so as to be associated with it in some way (excepting chemical combination in the case of absorption of matter) for a longer or shorter time, it is said to be absorbed by that substance. The nature of absorption differs, of course, with the nature of the thing absorbed and the nature of the absorbing substance. Thus gases are absorbed largely by some solids, the phenomenon being called Occlusion (q.v.) in this case. See also the articles on Solution, Fluorescence, Spectrum (for Absorption-spectrum), and especially that on Radiation of Heat. The term is also applied (1) in Animal Physiology to the osmosis of the dissolved matter of the chyle into the vessels of the intestinal villi; (2) in Vegetable Physiology, to the passage of water by endosmosis into the cells of the roots; and also (3) to the initial steps in the process by which the green parts of plants, in sunlight, absorb carbonic acid gas and decompose it. See PHYSIOLOGY, VEGETABLE CHEMISTRY. For absorption and absorbents in anatomy and medicine, see LACTEALS AND LYMPHATICS.