PURGATION, the art of purging, scouring, or purifying a thing, by separating or carrying off any impurities that may be found therein. Thus, in pharmacy, purgation is the cleansing of a medicine by retrenching its superfluities; in chemistry, it is used for the several preparations of metals and minerals intended to clear them of their impurities; and in medicine, purgation is an excretory motion arising from a quick and orderly contraction of the fleshy fibres of the stomach and intestines, whereby the chyle, corrupted humours, and excrements, lodged therein, are protruded further and further, and at length quite excluded by stool.