Resina (U. S. P.)—Resin.
Preparations: Resin Plaster - Compound Resin Plaster - Resin Cerate
Related entry: Oleum Terebinthinae (U. S. P.)—Oil of Turpentine - Oleum Terebinthinae Rectificatum (U. S. P.)—Rectified Oil of Turpentine - Terebinthina (U. S. P.)—Turpentins - Pix Liquida (U. S. P.)—Tar - Terebinthina Canadensis (U. S. P.)—Canada Turpentine
SYNONYMS: Colophony, Rosin.
Source.—The term Resin (see Resinae) here has a special meaning, being applied to "the residue left after distilling off the volatile oil from turpentine"—(U. S. P.). It is better known by the names of Rosin or Colophony. The manufacture of this article is one of the leading industries of the southern states (see Terebinthinaand Oleum Terebinthinae). Resina flava, or Yellow rosin, contains some moisture, in consequence of the distillation not being carried to dryness; it this, while in a melted state, be shaken with water, it forms a lighter colored resin, termed Resina alba, or White resin. Fiddlers' rosin, or Colophony, is a translucent, brownish-yellow substance, the result of the distillation being continued until all water is expelled, or without the use of water.
Description and Chemical Composition.—As officially required, resin is "a transparent, amber-colored substance, hard, brittle, pulverizable; fracture glossy and shallow-conchoidal; odor and taste faintly terebinthinate. Specific gravity 1.070 to 1.080. Soluble in alcohol, ether, and fixed or volatile oils; also in solution of potassium or sodium hydrate"—(U.S. P.). It is heavier than water and melts at a moderate heat. When kept in powdered condition, it is liable to undergo spontaneous combustion (H. Hager, Amer. Jour. Pharm., 1888, p. 455). When melted, it can be united with wax, fats, spermaceti, etc. Prof. Olmstead (Amer. Jour. Pharm., 1850, p. 325) states that rosin added to lard gives it a degree of fluidity not before possessed by the lard, and also prevents the latter from forming those acids which corrode metals. A compound of 1 part of rosin to 4 of lard, may be used for various purposes; by incorporating a certain amount of black-lead, and applying a thin coating to iron stoves and grates it prevents them from rusting, forming a complete protection. The principal constituent of rosin is abietic anhydride (C44H62O4, Maly, 1861-64) which dissolves in warm 70 per alcohol with absorption of water and formation of abietic acid (C44H62O5., which falls out upon cooling. This acid forms colorless small crystals soluble in alcohol, wood alcohol, chloroform, ether, benzene, carbon disulphide and glacial acetic acid. It also dissolves readily in caustic alkali with formation of a resin soap (e. g., sodium abietate). The acid absorbs oxygen upon exposure to the air. A series of esters (ethyl, methyl and glyceryl esters) of abietic acid has been prepared which have been used in the preparation of varnishes. By destructive distillation of the acid with reducing agents (zinc dust), homologues of benzene, naphtalene, and anthracene are formed.
Action, Medical Uses, and Dosage.—Rosin is seldom given internally. Its principal use is to form plasters and ointments, to which it is an excitant ingredient, and renders them more adhesive. Internally, pulverized rosin will be found very useful in doses of 30 to 60 grains in molasses, or linseed oil, 3 or 4 times a day, in bleeding piles. Applied locally, on lint or cotton, it will be found a very valuable styptic. The vapor from rosin has been inhaled in chronic bronchitis, and certain atonic affections of the lungs with benefit; and the fumes of burning rosin, if received upon the parts, will, it is said, remove the irritation attending piles and prolapsus ani. Half a drachm of powdered rosin, dissolved in a sufficient quantity of chloroform, so as to make a thick solution, will relieve neuralgia of the teeth, or toothache, by introducing a piece of cotton, which has been impregnated with the solution, into the hollow teeth.