Alum is a chemical compound of two distinct salts, namely: Sulphate of alumina and sulphate of potassa, or sulphate of alumina and sulphate of ammonia. The last salt is present only in a few varieties, and other specimens contain a soda salt with the salt of alumina, and still others substitute an iron salt for alumina. The following symbols represent the more familiar specimens: Roman or Rock Alum. KO.SO3+Al2O3+24HO. Ammonia Alum. NH~O.SO3+Al2O3+24HO. Iron Alum. KO. SO3+Fe2O3+24HO. The proportion of water is thus seen to remain uniform through them all, while the characterizing salt is a tersulphate of a sesquioxide.
Rock Alum is the one used in medicine. It is found in a nearly pure state in the volcanic region of Italy, and is purified by solution and subsequent crystallization. The almun ores are certain slaty earths, from which the alum is manufactured by calcination, exposure to the air for three months, and subsequent lixiviation and crystallization.
Properties and Uses: This is a pure, and among the least, irritating of the metallic astringents. Given in doses of five to fifteen grains every three or four hours, it has been used to check passive hemorrhages, and chronic dysentery and diarrhea. In solution of half a drachm to an ounce of water, it has been extolled as a gargle in scarlatina and other anginose affections, for ptyalism, and elongated uvula, and as an injection for uterine hemorrhages; while five to nine grains to the ounce form a wash in purulent ophthalmia, and (in some demulcent infusion) an injection in leucorrhea, gleet, and even gonorrhea. It will check mucous discharges in all these cases; but such a mere suppression is by no means a cure, and therefore the alum practice is a very poor one.
In doses of from forty to sixty grains every fifteen minutes, it is an emetic, and has been highly valued for this purpose in croup. In the same large dose, repeated every three hours, it proves purgative; and is said to allay the nausea and open the bowels more efficiently, in lead colic, than any other agent. It is reputed antispasmodic, and has been given in small doses, three times a day, in hooping-cough.
The article is chemically incompatible with the alkalies and their carbonates, as lime and lime water, magnesia and its carbonate, potassa and its carbonate, soda, tartrate of potassa, and acetate of lead–which it will neutralize and render nearly inert.
Pharmaceutical Preparations: When given internally, it is better to mix the fine powder with the sirup, or honey, than to give it in solution. Alum Whey is prepared by boiling two drachms of alum with a pint of milk, and straining to separate the curd. Burnt Alum is merely alum deprived of its water by heat. It is powdered and sprinkled upon fungous flesh, acting as a very mild escharotic.
The Physiomedical Dispensatory, 1869, was written by William Cook, M.D.
It was scanned by Paul Bergner at http://medherb.com