Common potash alum: A12(So4)3, K2So424h2o. Ammonium Alum: A12(Nh4)2(So4)4, 24H2O.


It is found native in Italy, in the neighborhood of volcanoes, and is the mineral from which the metal aluminum is obtained.


Alum is also obtained from aluminous slate, shale or schist, by the process of roasting and exposure to the air.

Alum is a white, slightly efflorescent salt, which crystallizes in regular octahedrons. It possesses an astringent, acid, and sweetish taste. It is insoluble in alcohol, but dissolves in from fourteen to fifteen times its weight in cold, and three-fourths of its weight in boiling water.

Medical Properties And Action

Alum is astringent and styptic, and is employed both externally and internally. When taken internally, it is absorbed into the system, and has been detected in the liver, spleen and urine. Excessive doses cause vomiting, griping, purging, and inflammation of the gastro-enteric mucous membrane. Powdered alum, in doses of a teaspoonful, is an efficient emetic. It coagulates albumen and causes an abundant flow of saliva, coagulating the albumen of the saliva and buccal mucus in whitish, membranous flakes.

Its astringent influence is chiefly upon mucous surfaces. Applied locally to relaxed or bleeding parts, it corrugates the surrounding tissues and causes contraction of the capillaries, and, in this manner, acts as an astringent.

Therapeutic Uses

Alum is internally administered in diarrhoea, chronic dysentery, colica pictonum, catarrh of the stomach, etc. Externally it is applied in ulcerated and relaxed throat affections, ptyalism, gonorrhoea and gleet, uterine hemorrhage, morbid growths, hematuria, ophthalmia, chronic whooping-cough, chronic skin diseases, chilblains, ulcers, hospital gangrene, etc., etc.


Of alum, gr. x to Dose 635 or in powder, or solution in water, or in some simple infusion.

Ammonia Alum

Sulphate of alumina and ammonia - Aluminae et Ammoniae Sulphas - is prepared by adding sulphate of ammonia to a solution of sulphate of alumina.

Dried Alum

Alumen Exsiccatum (alum deprived of its water of crystallization by heat) - is employed externally as a mild escharotic, to destroy exuberant granulations, etc.

Dental Uses

Alum is employed in dental practice as a styptic in alveolar hemorrhage; as a gargle in stomatitis, ulceration, and sponginess of the gums, morbid or fungous growth of gums, dental pulp, etc., superficial hemorrhage from the mucous membrane of the mouth, ulcers of the mouth, cancrum oris, odontalgia, after the extraction of teeth - one drachm in a tumbler of water, etc., etc. In congested conditions of the mucous membrane of the mouth and throat, alum gargles afford great relief. Powdered alum added to liquor sodae chlorinatae (Labarraque's Solution), is an excellent bleaching application for discolored necrosed teeth.

The habitual use of alum as an ingredient of a dentifrice is injurious to the teeth, on account of the sulphuric acid it contains.

Potash alum - Aliiminii et Potassii Sulphas - the alum of commerce (which has been superseded by ammonia alum), will render plaster casts hard, when they are boiled in a strong solution for half an hour.

Dental Formulae

For Odontalgia.

Pulveris aluminis . . AEtheris nitrici .... Signa. - To be applied on a pellet of cotton.

Dental Formulae 637Dental Formulae 638

For Inflamed and Ulcerated Mucous Membrane and Gums.

Pulveris aluminis . . Aquae destillatae . . Signa. - To be applied as a mild astringent gargle.

Dental Formulae 639Dental Formulae 640

For Ulceration of the Gums ana Mucous Membrane of the Mouth.


Zinci sulphatis . . .

Sodii borat.....

Aquae rosae.....


To be applied as a lotion.

Signa 641Signa 642

For Ulcerated and Spongy Gums.



Tinct. cinchonae . . Tinct. myrrhae . . .

Mel. rosae......


To be used as a gargle.

Signa 643Signa 644

For Inflammation and Ulceration of the Mouth and Throat.

Infus lini.............

Tinct. kino............



To be applied as a gargle.

Signa 645Signa 646