Encyclopædia Britannica, Ninth Edition/Benzoin

BENZOIN, Gum, sometimes called Gum Benjamin, a fragrant gum-resin obtained from Styrax Benzoin, a tree of considerable size, a native of Sumatra and Java, and introduced into Siam, Borneo, &c. The gum-resin is obtained by making incisions in the bark of trees after they have attained six years of age, when the benzoin exudes, and after hardening in the air is carefully scraped off with a knife. A tree produces on an average about 3 lb annually for 10 or 12 years. The produce of the first three years is known as "head" benzoin, and is esteemed the finest and most valuable; that produced in later years goes by the name of "belly" benzoin; and after the trees are cut down a small quantity of a dark-coloured and very inferior quality is obtained, which is called "foot" benzoin. In commerce the gum-resin is distinguished as Siam or Sumatra benzoin, according to the localities from which it is derived. Siam benzoin is generally regarded as the best, and of it two varieties are distinguished. The finest quality is Siam benzoin "in tear," it being in small flattened drops, from the size of an almond kernel downwards. "Lump" Siam benzoin consists of agglutinated masses of such tears, or of tears imbedded in a darker coloured resinous matrix. Tear benzoin varies in colour from a pale yellow to a reddish-brown colour, and lump benzoin has a conglomerate-like structure from the dissemination of almond-shaped tears throughout the substance. Sumatra benzoin has neither so strong nor so agreeable an odour as that of Siam, but the finest qualities are not found in the English market, being bought up for use in the religious rites of the Greek Church in Russia. Sumatra benzoin occurs in larger rectangular masses of a greyish tint, with few large tears in it, but containing small white opaque pieces, with chips of wood and other impurities, in a translucent matrix. Benzoin is composed of a mixture of three resins, distinguished by their behaviour towards solvents, and of benzoic acid, with sometimes cinnamic acid in addition; in some specimens of Sumatra benzoin cinnamic acid has been found entirely replacing benzoic acid. Usually benzoin contains from 12 to 18 per cent. of benzoic acid, the opaque white portions containing less than the brown resinous substance. It also contains traces of a highly odorous essential oil, like styrol, the aromatic oil present in storax. The quantity of benzoin exported from Sumatra in 1871 was about 16,000 cwt., while Siam sent out only 405 cwt., but very great quantities are used as incense in the religious ceremonies of the East, which indeed is the principal object for which it is brought into the commerce of Western nations. In medicine benzoin is seldom administered except as an adjunct to pectoral medicines. A compound tincture of benzoin is applied to flabby ulcers, and to excised wounds after the edges have been brought together. In these connections benzoin has a popular reputation under the name of Friars' or Monks' Balsam, which is a compound tincture of benzoin, and it forms an ingredient in court or black sticking-plaster. Benzoin diminishes the tendency towards rancidity in fats, a circumstance turned to account in the Adeps benzoatus of pharmacy.