ammoniac or gum ammoniac (əmōˈnēăkˌ) [key], yellowish substance with a sickening, bitter taste, obtained from the milky exudate of the injured stem of a plant ( Dorema ammoniacum ) found in Iran, India, and S Siberia. It is a gum resin, soluble in alcohol and ether. It is used in industry in the manufacture of porcelain cements and in medicine as an expectorant. When gum ammoniac is distilled, it yields a liquid, oil of ammoniac.
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