ALUM. 63 



pared by dissolving litharge, or the carbonate, in distilled vinegar, 

 by the aid of heat. 



ProiJ. — A white salt ; crystallizes in needle-shaped forms; odour, 

 peculiar; taste, sweetish and astringent; effloresces on exposure; 

 perfectly soluble in pure water, but gives a turbid solution, if there 

 be any carbonic acid present. Incompatibles, the mineral acids and 

 their soluble salts, the alkalies, alkaline earths, and vegetable as- 

 tringents. 



Uses. — Internally, in hemorrhages, particularly hsemoptysis ; also 

 in dysentery, cholera-infantum, and in certain disorders of mucous 

 membranes, as in yellow fever, and malignant remittents and inter- 

 mittents. Dose, gr. ss. to gr. ij, every two or three hours, according 

 to circumstances. Used very much as a topical application, parti- 

 cularly in inflammations of the mucous membranes and the skin. 

 The strength of the solution, for mucous membranes, is from gr. ss. 

 to gr. ij in a f5 of water ; for the sound skin, 3ij, dissolved in Oj of 

 water. 



Solution of the Subacetate of Lead, — Liquor Plumbi Suhacetatis 

 — [GoidarcVs Extract.) — Prepared by boiling together equal quan- 

 tities of sugar of lead and litharge. It is not uniform in its strength, 

 varying with the quantity of lead contained in the preparation. It 

 is a colourless, limpid fluid, having a sweetish astringent taste. It 

 is decomposed by whatever is incompatible with the acetate, and also 

 by gum and starch. It must be preserved in closely stopped bottles, 

 to keep it from the carbonic acid of the air. 



Uses. — Never internally ; externally, diluted, to sprains, bruises, 

 burns, and ulcers, in the proportion of 3ij or 3iij to the Oj of water. 



Lead Water — Liquor Plumbi Subaoetatis Dilutus — contains 

 only 3j to Oj of water. 



Goulard's Cerate — [Ceratuni Plumbi Subacetatis, U.S.) — is 

 made by boiling together Goulard's extract, white wax, olive oil, 

 and camphor: it is an excellent application to abraded surfaces, and 

 to blisters not disposed to heal. 



Alum. — (Alumen, U. S.) 



Chemically, a double sulphate of alumina and potassa ; some- 

 times found native, though usually made artificially, either from 

 some of the native ores of alum, or by a direct combination of the 

 elements. Some varieties of alum contain sulphate of soda, or sul- 

 phate of ammonia, instead of sulphate of potassa. 



Prop. — A white crystalline salt, slightly efflorescent, crystallizes 

 in regular octohedrons ; taste, sweetish and astringent ; very solu- 

 ble in hot water, which deposits crystals on cooling; reddens lit- 

 mus ; when heated, undergoes the aqueous fusion, and is converted 

 into dried alum {cdurtien exsiccatum.) The alum of commerce ge- 

 nerally contains some iron as an impurity. 



