Contractions. - Alum. Alm.

Present name. - Alumina. A12O3, 3H1O.

Pure Clay. For. names: German, Thon-erde, Alaun-erde; French, Alumine.

This should be prepared by precipitating Ammonia Alum with Solution of Ammonia as follows: -

Take of

Ammonia Alum in crystals . . .

1 ounce;

Stronger Solution of Ammonia B.P.

1/2 fluid ounce;

Distilled Water ....

A sufficiency.

Powder the Alum and dissolve it in 10 fluid ounces of warm distilled water; add the Ammonia, collect the precipitate on a calico filter, and wash it with hot distilled water until the washings give no precipitate with Chloride of Barium, or any odour of Ammonia when mixed with Caustic Potash and boiled. The Alumina is then carefully dried on a water bath and pulverized.

Characters. - A very fine white powder, soft to the touch, tasteless, infusible, forming a paste with water, but not dissolving in it.

Preparation. - Trituration.

Reference to Horn. Proving. - Chr. Kr., ii.

Proper forma for dispensing. - lx to 3, Trituration only. 4, dilute Tincture only. 5 and upwards, Tincture, Pilules, or Globules.

The salts formed by Alumina with Acetic, Malic, and Tartaric Acids are all readily soluble in water, and one or other of these, especially the Acetate, might be used instead of the trituration of the pure Alumina by those who prefer solutions to triturations.