Ammoni'acum

Ammoni'acum, or AMMO'NIAC, a gum resin, used in medicine on account of its stimulant and expectorant qualities, is obtained from Dorema Ammoniaæum, a plant of the natural order Umbelliferae, a native of Persia—a perennial about seven feet high, with large doubly pinnate leaves. The leaves are about two feet long. The whole plant is abundantly pervaded by a milky juice, which oozes out upon the slightest puncture, and which hardens, and becomes ammoniacum. The ammoniacum exudes from punctures made by a beetle, which appears in great numbers at the time when the plant has attained perfection. It occurs in commerce either in teats, or in masses formed of them, but mixed with impurities. It is whitish, becoming yellow by exposure to the atmosphere, is softened by the heat of the hand, and has a peculiar heavy unpleasant smell, and a nauseous taste, at first mucilaginous and bitter, afterwards acrid. It is not fusible, but burns with white crepitating flame, little smoke, and strong smell.