This section is from the book "Materia Medica And Therapeutics: An Introduction to the National Treatment of Disease", by John Mitchell Bruce. Also available from Amazon: The pharmacology and therapeutics of the materia medica.
Benzoinum-Benzoin.-A balsamic resin obtained from Styrax Benzoin. It is procured by making incisions into the bark of the tree, and allowing the liquid that exudes to concrete by exposure to the air. Imported from Siam and Sumatra.
Characters.-In lumps, consisting of agglutinated tears, or of a brownish mottled mass with or without white tears imbedded in it; has little taste, but an agreeable odour ; gives off, when heated, fumes of benzoic acid; is soluble in rectified spirit and in solution of potash.
Substances resembling Benzoin: Gum resins, and resins distinguished by odour and taste.
Composition.-Benzoin consists chiefly of four different resins, imperfectly known, with the officinal benzoic acid, cinnamic acid, and a trace of volatile oil.
Adeps Benzoatus. 10 gr. to 1 oz.
Tinctura Benzoini Composita. " Friar's Balsam." Benzoin,
8; Prepared Storax, 6; Balsam of Tolu, 2; Socotrine Aloes, about 1 1/2; Spirit, 80. Dose, 1/2 to 1 fl.dr.
From Benzoinum is made:
Acidum Benzoicum. Benzoic Acid. HC7H502. Source.-Prepared from Benzoin by sublimation. Characters.-Light feathery crystals, nearly colourless, having an aromatic odour. Soluble in 400 of cold water, in 12 of boiling water, in 4 of spirit. Phosphate of soda or borax aids its solubility in water, so that 1 of borax and 1 of acid are soluble in 100 of water. Dose, 10 to 15 gr.
From Acidum Benzoicum are prepared: a. Tinctura Camphorae Composita.-2 gr. to 1 fl.oz.
b. Tinctura Opii Ammoniata.-9 gr. to 1 fl.oz. See Opium.
From Acidum Benzoicum is made:
Ammoniae Benzoas.-NH4C7H502. Colourless laminar crystals with the fragrant odour of benzoic acid, made by dissolving benzoic acid in solution of ammonia and water, evaporating and crystallising. Soluble in 5 of water; in 18 of rectified spirit. Sublimes without residue. Incom-patibles.-Persalts of iron, liquor potassae, and acids. Dose, 10 to 20 gr.
Externally.-Benzoin and its preparations are antiseptic and disinfectant, and at the same time slightly stimulant to the vessels. The compound tincture, or "Friar's Balsam," has been long used as an application to ulcers and foul wounds, and also to promote the healing of freshly incised wounds.
Internally.-Benzoin and its acid cause sneezing and coughing when inhaled or applied in the solid form to the nose; much diluted with watery vapour, they are mild stimulants. The compound tincture is thus a useful substance for inhalation or spray in many laryngeal diseases; and benzoic acid has been applied direct to the affected surface in diphtheria, where it acts also as a disinfectant.
Benzoin and benzoic acid enter the blood in the form of benzoate of sodium, and here, as well as in the kidneys, this acid is partly converted into hippuric acid by combination with a molecule of glycocoll, thus:- C7H602 + C2H5N02 (glycocoll) = C9H9N03 (hippuric acid) + H10. The exact source of the glycocoll is still obscure. It is not derived from the urea or uric acid, as was once suggested; and the use of benzoic acid to take up and carry out by the urine excess of urea in uraemia, or excess of uric acid in gout, is erroneous in theory, as it has failed in practice.
Benzoic acid and its salts act upon nutrition very much like the salicylates, as far as they have been investigated ; that is, they are antipyretic, whilst they are said to increase metabolism. They have been used to lower the temperature in pyaemia, acute rheumatism, and specific fevers; but their effects are very uncertain, and frequently very unpleasant. Their internal use in phthisis has quite failed, and in diphtheria they are of doubtful value.
Benzoic acid is excreted by the kidneys, partly unchanged, partly as hippuric acid, and occasionally as succinic acid, increasing the flow of urine ; by the skin and salivary glands, unchanged, stimulating their secretions ; and probably by the respiratory organs, decidedly increasing the amount of expectoration. These remote local effects are turned to useful account. The acid and its ammonia salt are extremely valuable in inflammation of the bladder with alkalinity of the secretion and phosphatic deposits, by acidulating the urine and stimulating and disinfecting the mucous surfaces; and they are used all the more that they are almost the only certain means of neutralising morbid alkalinity of the urine which we possess. As an expectorant, benzoic acid, chiefly as the compound tincture, or contained in Tinctura Camphorae Composita, Tinctura Opii Ammoniata, and the balsams of Tolu and Peru, is very useful in chronic bronchitis, when the bronchial products are abundant, thick, possibly foul, the mucous membrane chronically inflamed and weak, and reflex activity low.