ABSORPTION

In general, the taking up of one substance by another substance. In chemistry, it could be the absorption of a gas by a liquid or a solid. The coefficient of absorption of a gas is the amount of the gas absorbed by a unit volume of liquid. In physics, absoprtion can be the loss of energy of sound waves or electromagnetic radiation to the medium in which they travel. The degree of reflection, and hence absorption of light by a substance, for example, determines its color. Total absorption of light produces black; total reflection, white. In physiology, absorption usually denotes a series of processes in which an organism takes in and distirbutes various constituents. Fats, for example, are absorbed through the intestine walls into the blood stream. When radiation passes through certain gases or fields, spectrum analysis reveals discontinous, dark bands. These bands indicate what is known as selective absorption; the bands themselves are called absorption bands. They are produced by the selective absorption of particular wave lengths by the medium. An unknown chemical compound, for example, can be identified by its characteristic absoprtion bands. Sound waves are absorbed to some extend by all building materials. Acoustical materials are those surfaces especially manufactured to have high coefficients of sound absorption.