BENZOIN′, B. P. (-zoyn′; zō′-ĭn). Syn. Gum-benzoin*‡, Ben′jamin†*, Gum-b.†*; Benzöi′num, L., B. P.; Benjoin, Fr.; Benzöe, Ger. The balsamic resin exuded from incisions made in the stem of the styrax benzoin, a native of Sumatra, Java, Borneo, Laos, and Siam. Several varieties of benzoin are in the market; two only, however, are chiefly used in medicine, one in agglutinated masses, the other (from Siam), in tears, being the purer and having the stronger odour.
Prop., &c. Odour agreeable, and somewhat like that of vanilla, but more balsamic; fracture conchoidal; lustre greasy; sp. gr. 1·063 to 1·092. It fuses at a gentle heat and exhales white fumes, which, on condensation, are found to be benzoic acid contaminated with a little volatile oil. Alcohol dissolves the larger portion of it, ether much less, and the volatile and fixed oils only a little. It contains from 9% to 18, or (occasionally) nearly 20%, of benzoic acid, according to the quality. It burns with an agreeable odour. The resin and its alcoholic solution strike a bright red colour with oil of vitriol, and a green colour with chloride of iron.
Benzoin has occasionally been sold by fraudulent dealers after its benzoic acid has been removed by the wet method. When the gum has been thus treated it will not show the agglutinated tears, upon fracture, which commonly distinguishes it when intact.
Uses, &c. It is chiefly employed in perfumery, and as an ingredient in incense, fumigating pastilles, &c.; also in court-plaster, in certain cosmetics, and to scent the varnish used for snuff-boxes, walking-sticks, &c. As a medicine, its general effects resemble those of the other true balsams, and of benzoic acid.—Dose, 5 or 6 to 20, or even 30 gr., in powder, and usually in combination with some other remedy; chiefly in chronic pulmonary and bronchial affections, when occurring in torpid habits, and unaccompanied by inflammatory symptoms or gastric irritation. Also as a fumigation in the same diseases, hooping-cough, &c. Like benzoic acid, it is used to prevent rancidity in ointments, pomades, and other fatty preparations.
BENZOINUM. See Benzoin.
BEN′ZOL (-zōle). C6H6. [benz(oin)-oleum.] Syn. Ben′zene*, Ben′zĭne, Ben′zōle*, Hydrĭde of phe′ny̆̆l*, Phe′ne†, &c.; Benzo′leum, L.; Benzine, Fr.; Benzöl, Ger. A peculiar ethereal hydrocarbon discovered, by Faraday, among the products of the destructive distillation of whale oil and other organic substances (A.D. 1825); and subsequently shown, by Mitscherlich, to form the principal ingredient in the distillate procured by the action of heat on a mixture of benzoic acid and hydrate of lime. In 1849, Mr C. B. Mansfield[154] discovered its presence in coal-tar naphtha, from which the benzol of commerce is now chiefly, if not wholly, obtained.
[154] This unfortunate chemist lost his life (Feb. 25, 1855), in consequence of being severely burned whilst experimenting on benzol.
Prep. 1. Pure:—a. A mixture of benzoic acid, 1 part; fresh-slaked lime, 3 parts; is submitted, in a coated glass or earthenware retort, to a heat slowly raised to redness; the oily portion of the resulting distillate is then separated from the water, and carefully rectified, with the proper precautions, at a temperature not exceeding 190° Fahr. The product is usually stated to be pure benzol; but to ensure this it may be submitted to one refrigeration and rectification, in the manner and at the temperature noticed below.
b. From good commercial benzol, agitated with 1-4th or 1-5th of its weight of concentrated sulphuric acid, and, after repose and decantation, rectified at a temperature under 195° Fahr.; the resulting distillate is exposed to a temperature below[155] 32° Fahr., and the mass of crystals that form are thrown on a funnel, kept at the same temperature, to drain, after which they are pressed between folds of
bibulous paper,[156] and then allowed to liquefy by simple exposure, in a close vessel, to the ordinary temperature of the atmosphere. The product, after rectification at a temperature not exceeding 190,° is nearly pure benzol. It may be rendered absolutely pure by repeating the refrigeration a second and a third time, followed by a final rectification at 180-185° Fahr.