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A double sulfate of aluminum and of an alkaline earth element or ammonium; chemically, an alum is any one of the markedly astringent double salts formed by a combination of a sulfate of aluminum, iron, manganese, chromium, or gallium with a sulfate of lithium, sodium, potassium, ammonium, cesium, or rubidium; used locally as a styptic.
1. a local astringent and styptic, prepared as an ammonium (ammonium a.) or potassium (potassium a.) compound; also used as an adjuvant in adsorbed vaccines and toxoids.
2. any member of a class of double sulfates formed on this type.
Any of various double sulfates of a trivalent metal such as aluminum, chromium, or iron and a univalent metal such as potassium or sodium, especially hydrous aluminum potassium sulfate, AlK(SO4)2·12H2O, widely used in industry as clarifiers, hardeners, and purifiers and medicinally as topical astringents and styptics.
Etymology: L, alumen
a topical astringent, used primarily in lotions and douches.
Agent used locally as a styptic.
any of several substances, including potassium alum, aluminum alum, ammonium alum, potash alum and aluminum potassium sulfate, with strong astringent properties. May be used as a styptic or hemostatic and as a topical antimycotic agent. It also may be given by mouth to induce vomiting. Large doses may cause gastrointestinal disturbances.