Alum

(al'-um). Any one of a cla of double sulphates formed by the union of one of the sulphates of certain non-alkaline metals with a sulphate of some alkaline metal. The standard (or common commercial) alum, the official A lumen, U. S. P., is the aluminium-pota ium sulphate, -f- -f- It is a powerful astringent and styptic in medicine, and is extensively used in the arts. It is employed by bakers to whiten their bread, but the effect upon the system is probably injurious. Ordinary A. Ammoniae is the same as the above, except that the pota ium is replaced by ammonium. It is official in Great Britain, and is extensively used on account of its cheapne . What is known as concentrated or patent alum, is the normal aluminium sulphate. A. Ammonio-ferric (Ferri et Ammonii sulphas), U. S. P., is strongly styptic, and is useful in leucorrhea. Dose gr. v-x. A. Pota io-ferric is extremely similar to the A. ammonio-ferric. (For A. Rubidium, see Rubidium). A. Sodae, double sulphate of sodium and aluminium, is too soluble for ordinary uses. The other alums are very numerous, but they are of little interest to the physician. A. Whey, a preparation obtained by boiling ij of alum in a pint of milk, and straining. It is used as an astringent and internal hemostatic, in winegla ful doses.