(From extraho, to draw from). Extraction. The liquors which dissolve bodies in then-pure state, separate them from impurities, or rather extraneous bodies with which they are mixed. Extraction is performed by macerating the subject in its appropriated menstruum in the cold; by digesing or circulating it in a moderate warmth; by infusing it in a boiling fluid, and suffering them to stand until they are cold; or by actually boiling it for some time. Heat greatly expedites extraction; but it is injurious to some substances, by occasioning the menstruum to take up their more gross and disagreeable parts: yet others impart but little to a heat below that of boiling water. As heat promotes, so cold prevents, extraction, and occasions a deposition of what heat had enabled the menstruum to take up.
Vegetable juices obtained by expression, exposed to a heat, are gradually inspissated; and the mass is now styled, instead of an extract, an inspissated juice. The term extract is still retained, when a watery decoction or infusion is evaporated; but if a spirituous tincture be thus treated, it is called a resin or essential extract. Dr. A. Duncan proposes to call extracts extractives; but the latter is a component part of vegetables of a peculiar nature, and the former any thing separated.
Inspissated juices, when evaporated only to the consistence of honey or oil, are called rob, or sapa. Spirituous tinctures reduced to a like consistence are called balsam. See the New Edinburgh Dispensatory, by Andrew Duncan,jun. M. D.
Extraction, in surgery, is the drawing from or out of the body any thing fixed in it, as a thorn or a bullet in the flesh, a tooth from the jaw, or hairs from the skin.