1. Alumen. Alum

Alumen. Alum. A12K2(So4)2+24H2O=946.46. Synonyms. - Aluminum and Potassium Sulphate. Potassium Alum.


Made from Alum Slate or Shale (a mixture of Aluminum Silicate and Iron Sulphide) by roasting and exposing to the air. By lixiviating the heaps with water, Sulphuric Acid, Aluminum and Iron Sulphates are obtained in solution. This solution is concentrated, and while hot mixed with Potassium Chloride, which, reacting upon the Ferric Sulphate, yields Potassium Sulphate and Ferric Chloride, while the Alum separates on cooling as a crystalline powder. It is then purified by one or two recrystallizations. Also by making an Aluminum Sulphate from Al(OH)3, the by-product in the manufacture of Soda from cryolite.


Large, colorless, octahedral crystals, sometimes modified by cubes, or in crystalline fragments, without odor, but having a sweetish and strongly astringent taste. On exposure to the air, the crystals are liable to absorb ammonia, and acquire a whitish coating. Solubility. - In 9 parts of water.


Alkalies, lime, lead, mercury, and iron salts, tartrates and tannic acid.


Ferrous sulphate and silicates. Dose, 5 to 30 gr.; .30 to 2.00 gm.


Alumen Exsiccatum

Dried Alum. Synonyms. - Alumen Ustum. Burnt Alum.


Heat 100 parts of Alum with moderate heat till aqueous vapor ceases to be disengaged, and it is reduced to 55 parts.


A white, granular powder, without odor, possessing a sweetish, astringent taste, and attracting moisture from the air. Solubility. - Slowly but completely soluble in 20 parts of water.

2. Alumini Hydras. Aluminum Hydrate

Alumini Hydras. Aluminum Hydrate. Al2(OH)6=155.84. Synonyms. - Aluminum Hydroxide. Hydrated Alumina.


By separate solution of Alum, 100; and Sodium Carbonate, 100 in distilled water and heat. Mix the hot solutions, wash the precipitate with hot distilled water, dry and reduce to a fine powder.


A white, light amorphous powder, odorless and tasteless, permanent in dry air. Solubility. - Insoluble in water or Alcohol.

Dose, 1 to 10 gr.; .06 to .60 gm.

3. Alumini Sulphas. Aluminum Sulphate

Alumini Sulphas. Aluminum Sulphate. Al2(So4)3+l6 H2O=628.9.


Aluminum Hydroxide, Al(OH)3, a by-product in the manufacture of Soda from cryolite, is dissolved in diluted Sulphuric Acid; the solution is filtered and evaporated to dryness.


A white, crystalline powder, without odor, having a sweetish and afterwards astringent taste. Solubility. - 1.2 parts of water; almost insoluble in Alcohol.