Resin, commonly called rosin, is an abundant constituent of the exudations from several species of pinus and abies, where it is in combination with more or less turpentine. It is found as the residuum after the turpentine has been distilled off. Various roots, bark, and woods contain resinoid substances, not in combination with turpentine, as podophyllum, guaiacum, etc.; but this is not the class of resins here alluded to.
The true (or terehinthinate) resins are smooth and brittle, breaking with a shining fracture, nearly transparent, of a yellowish tint, and often with only a trifling odor or taste, though many times bitterish and acrid. At a temperature of about 280 deg.F. they melt; at 900 deg.F. they ignite, burning with a yellow flame and large volumes of black smoke; and if thus heated in suitable retorts, are decomposed into a large volume of superior illuminating gas. Water has no action upon them; but ether and alcohol dissolve them more or less readily, while the addition of water to such solutions occasions first a dense and milky-yellow turbidity, and afterwards a precipitation of the resin. The last-named facts pertain to the resinoids. Resins also unite with concentrated solutions of potassa and soda, and form soluble soaps. When melted, they unite readily with wax and the fixed oils. Common resin is a clear yellowish-brown color, sometimes almost black, and heavier than water. By boiling it in a weak solution of carbonate of potassa, a thin soap is formed; and if the vapor of sulphurous acid is conveyed into this till the potassa is occupied, the resin will fall as a nearly white, opaque, and flaky mass.
Uses: Resin is not employed internally, though some physicians commend doses of five to ten grains as a stimulating diuretic. It is used as an ingredient in a large variety of plasters, both to give them firmness and to preserve the fatty matters–a property possessed to a considerable extent by the resins. Its own action is moderately and rather persistently stimulating.
Pharmaceutical Preparations: I. Resin Cerate, Basilicon Ointment. Melt together eight ounces of lard, five ounces of resin, and two ounces of beeswax; strain, and stir constantly till cool. A gently stimulating dressing for indolent ulcers and burns; and one that may be used as a basis for other medicaments.
II. Compound Resin Ointment, Deshler's Salve. One pound each of resin, suet, and beeswax, half a pound of turpentine, and half a pint of flaxseed oil. Melt and treat as in the foregoing. This is rather more stimulating than the basilicon ointment, but is employed for the same general purposes.
The Physiomedical Dispensatory, 1869, was written by William Cook, M.D.
It was scanned by Paul Bergner at http://medherb.com