Guaiaci resina. Guaiac.
The Concrete Juice of Guaiacum Officinale.
History. — The resin of Guaiacum, or gum guaiacum as it is erroneously called by some, is obtained from the wood of the tree, in several different modes ; by spontaneous exudation, by incisions made into the tree, or by boiling the chips or sawdust from the wood in a solution of common salt, and skimming off the substance which floats to the surface. This last is the method most commonly pursued. Guaiac is imported from the West Indies in irregular lumps of various sizes, combined with more or less impurities, as bark, sand, earthy matters, etc. Its surface is brownish-red, or brownish-yellow when recent, but becomes greenish-brown under exposure to the air. It is brittle, presenting a splintery vitreous fracture with some translucency. Its odor is feeble but fragrant, and is increased by heat. Its taste, at first scarcely perceptible, is faintly bitter, and sweetish, succeeded by a permanent sense of heat and pungency in the mouth and fauces. It pulverizes readily, and the powder, at first of a light-gray color, becomes greenish on exposure to the light, and in the air it becomes somewhat tenacious, quickly aggregating. A very moderate heat melts it. Alcohol dissolves it readily, forming a dark reddish-brown fluid, from which the guaiac is precipitated by water, by sulphuric or muriatic acid. Ammoniated alcohol, or solutions of the fixed alkalis dissolve it. Ether does not readily dissolve it; fixed and volatile oils scarcely at all. Water dissolves about nine parts in one hundred of the resin, becoming colored greenish-brown and having a sweet taste; and upon evaporating the water from the infusion a brown substance is obtained which is soluble in hot water or alcohol, but hardly at all in ether. Sulphuric acid forms with guaiac a deep-red solution ; nitric acid converts it into oxalic acid and an extractive matter, without producing any artificial tannin. Its specific gravity varies from 1.2 to 1.23. Analysis has found in it resin and a trace of benzoic acid.
Guaiac is subject to adulteration with pine resin, and other substances; this may be detected by observing, that the genuine article when freshly fractured is green, not red ; that the tincture of the spurious article will not render the recently-cut surface of a potato, carrot, or other plants containing gluten or milk, mucilage of gum Arabic, etc., blue — which change will be effected by the tincture of the genuine guaiac ; that when heated, guaiac does not exhale a turpentine odor; that oil of turpentine dissolves resin, but not guaiac ; and that paper which has been moistened by the tincture of guaiac, speedily becomes blue on exposure to the vapors of nitric acid. The mineral acids are incompatible with the solutions of guaiac.
The pure resinoid principle of guaiac, obtained by ether from the resin, by a process similar to that named in the preceding article for procuring it from the wood, is named Guaiacin. It is readily soluble in alcohol, less so in ether, and insoluble in water. It forms soluble compounds with the alkalis, which are decomposed by mineral acids, and several salts, on which account it has been termed Guaiacic acid. The resin of guaiac, according to Jahn, consists of three distinct resins, one soft, and soluble in ether or ammonia, and forming 18.7 per cent, of the crude drug ; another, likewise soft, soluble in ether, but scarcely in ammonia, constituting 58.3 per cent.; and the third, hard, soluble in ammonia but not in ether, amounting to 11.3 per cent.
Properties and Uses. — Guaiac is stimulant and alterative. Soon after being swallowed it produces a sense of warmth in the stomach, which is followed by slight increase of the pulse and temperature, dryness of the mouth, thirst, and diaphoresis or diuresis, depending upon the temperature at which the body is kept during its exhibition. Large doses act as a cathartic. It is used in the same affections as the Guaiaci Lignum, or guaiacum wood. Several practitioners have found it beneficial in amenorrhea, dysmenorrhea, and other uterine diseases ; likewise in acute dysentery, in which its employment is said to be followed by speedy beneficial results. It is much used in chronic rheumatism, and in the declining stages of the acute form, and has proved a most valuable agent in these diseases. It is said to be an antidote to the effects of the tincture of Rhus Toxicodendron. If the preparations of guaiacum produce sickness, defective appetite, and irregularity of the bowels, their use must be discontinued. Dose of the powdered resin, from five to twenty grains ; of the tincture, from one to four fluidrachms, either of which may be repeated three or four times a day. A mixture of ten grains each of guaiac and compound powder of ipecacuanha and opium, has been found of advantage in rheumatism and dysentery.
Off. Prep. — Tinctura Guaiaci; Tinctura Guaiaci Aromatica ; Tinctura Guaiaci Ammoniata.
The American Eclectic Dispensatory, 1854, was written by John King, M. D.
