Description. Benzoin occurs either in the form of reddish-white tears, separate or slightly adherent, or more frequently in masses consisting of the tears completely agglutinated with a brownish-red substance; on fracture, it presents an amygdaloid appearance; this forms Siam benzoin. Benzoin has little taste, but an agreeable odour. An inferior darker kind, called Calcutta benzoin, is sometimes met with.

Prop. & Comp. Benzoin contains from 10 to 20 per cent. of Benzoic acid; the remainder consists of a resin, partly soluble in ether. Benzoin is soluble in alcohol and liquor potassas; and gives off, when heated, fumes of benzoic acid. Benzoic acid (Ho C14 H5 O3), when pure, forms soft, feathery, flexible, white crystals, with a pearly lustre; generally impregnated with empyreumatic oil, which gives it a strong odour; slightly soluble in water, but readily so in rectified spirit; it is dissolved also by solutions of ammonia, potash, soda, and lime, from which it is precipitated by hydrochloric acid, unless the solution be very dilute. When heated it should sublime without residue.

Off. Prep. Tinctura Benzoini Composita. Compound Tincture of Benzoin. (Benzoin coarsely powdered, two ounces; prepared storax, two ounces; balsam of tolu, half an ounce; Soco-trine aloes, one hundred and sixty grains; rectified spirit, one pint. Prepared by maceration.)

Benzoic Acid is prepared by subliming benzoin in an iron vessel, and collecting the sublimed acid by means of a cylinder of stiff paper inserted over the vessel.

Benzoic acid is contained in Tinctura Camphorae cum Opio.

Therapeutics. Benzoin is a stimulant expectorant, formerly used in chronic bronchitic affections; externally in the form of the tincture (Friar's Balsam) it is applied as a stimulant to ulcers and wounds. Benzoic acid, when taken internally, is converted into and appears in the urine as hippuric acid, rendering the fluid more acid and somewhat irritating, but not diminishing the amount of uric acid: it is sometimes useful in catarrhus vesicas attended with alkaline urine, etc.

Dose. Of benzoin, 10 gr. to 30 gr.: of the compound tincture, 1/2 fl. drm. to 1 1/2 fl. drm., suspended in water by means of mucilage or yolk of egg; of benzoic acid, 10 gr. to 15 gr. Benzoate of Ammonia is described under Salts of Ammonia.