EXTRAC′TIVE

Syn. Extractive principle . Fourcroy entertained the belief that all vegetable extracts contained a common basis of definite composition, to which he gave the name of extractive . Chevreul and other chemists have shown, however, that Fourcroy’s extractive is not a chemical compound but a heterogeneous mixture, varying in composition with the plant from which it is obtained. Extractive has a brown colour, or one becoming so in the air; it speedily putrefies, and becomes oxidised, and is rendered insoluble by long exposure to air, and by repeated solutions and evaporations. In its unaltered state it is soluble in water and in alcohol, is nearly insoluble in ether, and is precipitated from its solutions by the acids and metallic oxides. With alumina it forms the basis of several brown dyes.