Acacia. B.P. 1958
Compiled and edited by
Ivor Hughes.

ACACIA
Acac. Gum Acacia
Acacia is the dried gummy exudation from the stem and branches of Acacia senegal Willd. and of some other species of Acacia.

Description.
Rounded or ovoid tears of varying size, usually about 0.5 to 6.0 cm. in diameter, nearly colourless or pale amber, opaque from the presence of numerous minute fissures, brittle, breaking into transparent, angular fragments with glistening surfaces. Almost odourless; taste, bland and mucilaginous.

Identification.
A. To 5 ml. of a 2 per cent w/v solution add 1 ml. of strong lead subacetate solution; a flocculent white precipitate is produced.

B. Dissolve 0.25 g. in 5 ml. of water by shaking in the cold, add 0.5 ml. of hydrogen peroxide solution and 0.5 ml. of a 1 per cent w/v solution of benzidine in alcohol (90 per cent), shake and allow to stand; a deep blue colour is produced.

C. Mount a small quantity, in powder, in ruthenium red solution, and examine microscopically; the particles do not acquire a red colour (distinction from agar and from sterculia).

D. To 10 ml. of a 2 per cent w/v solution, add 02 ml. of a 20 per cent w/v solution of lead acetate; no precipitate is produced (distinction from agar and from tragacanth).

E. To 0.1 g. in powder add 1 ml. of N/50 iodine; the mixture does not acquire a crimson or olive-green colour (distinction from agar and from tragacanth).

Solubility in alcohol.
Insoluble in alcohol (95 per cent).

Solubility in water.
Almost entirely soluble in an equal weight of water, yielding a translucent, viscous, slightly acid solution which is not glairy and, when diluted with more water and allowed to stand, does not yield a gummy deposit.

Optical rotation.
A 10 per cent w/v solution is slightly laevorotatory. Starch and dextrin. To 10 ml. of a previously boiled and cooled 10 per cent w/v solution, add 0.1 ml. of N/10 iodine; no blue or brown colour is produced.

Tannin.
To 10 ml. of a 10 per cent w/v solution, add 0.1 ml. of ferric chloride solution; no bluish-black colour is produced.

Insoluble matter.
Not more than 0.5 per cent, when determined by the following method: mix 5 g. in powder with 100 ml, of water and 10 ml. of dilute hydrochloric acid and boil gently for fifteen minutes, stirring frequently. Filter while hot through a sintered glass crucible, wash the residue with hot water, and dry to constant weight at 105�.

Acid-insoluble ash.
Not more than 0.5 percent.

Ash.
Not more than 5.0 per cent.

Loss on drying.
When dried to constant weight at 105�, loses not more than 15.0 per cent of its weight.

POWDERED ACACIA (Acaciae Pulvis)
Description.
White; in colourless angular microscopic fragments which, when treated with water, rapidly diminish in size and finally disappear.

Identification;
Solubility in alcohol; Solubility in water; Optical rotation; Starch and dextrin; Tannin; Insoluble matter; Acid insoluble ash; Ash; Loss on drying. Complies with the requirements for Identification, Solubility in alcohol, Solubility in water, Optical rotation, Starch and dextrin, Tannin, Insoluble matter, Acid-insoluble ash, Ash, and Loss on drying stated under Acacia.

Preparation.
Compound Tragacanth Powder.