Guaiacum Pharm. Lond. & Edinb. Guaiacum americanum primum fructu aceris five legitimum Breyn. prodr. Guaiacum officinale Linn, Guaiacum: a large tree, with roundish boxlike winged leaves, pentapetalous blue flowers in clusters, and a maple-like heart-shaped fruit including asingle seed (a), a native of Jamaica, Hispaniola, and other warm parts of America; from whence the wood with its bark, and a concrete resinous juice exuding from incisions made in the trunk, are brought to us. The wood is called by some lignum vitae and fanctum.

The wood is very hard, compact, and so heavy as to fink in water: the outer part is of a pale yellowish colour, the heart of a dark blackish brown with a greater or less admixture of green. It scarcely discovers any smell, un-lefs heated, or while rasping; in which circum-stances it yields a light aromatic one: chewed, it impreffes a mild acrimony, biting the palate and fauces. Its pungency resides in a resinous matter, which is totally extracted by digestion in rectisied spirit, and partially by boiling in water: the spirituous tinctures are of a deep brownish red colour, the watery decoctions of dark yellowish brown. On infpiffating the liquors, nothing of the pungency of the guaiacum exhales or distills with either menstruum: the spirituous extract, nevertheless, discovers but little of the pungent taste which prevailed in the tincture, proving a tenacious almost pure resin, not dissoluble in the mouth or miscible with the saliva: the watery extract, which contains likewise no small proportion of resinous matter, dissolves slowly, and then manifests a notable degree of pungency. During the infpiftation of the watery decoction, the resinous part is apt to separate and subside, unless a little spirit be added towards the end of the process to keep it united with the gummy: this extract is kept in the shops in a soft and a hard form; the first of a proper consistence for making into pills, the latter for being reduced into powder. The quantity of solid extract obtained by rectisied spirit amounts to about one fourth the weight of the wood; with water scarcely one sixth is obtained. After a pound of the shavings of the wood has been boiled in a gallon of water till half the liquor is wafted, and the coction suc-cessively repeated with five or six fresh gallons of water, a considerable portion of resin may still be extracted by moderate digestion in rectified spirit.

(a) Sloane, Catalogus plant arum in insula Jamaica, p. 186. Voyage to Jamaica, vol. ii. p. 133.

The bark of guaiacum is considerably less hard, but not much lighter, than the wood: it is thin, smooth, composed as it were of a number of fine plates joined closely together, externally of a blackish grey colour variegated for the most part with greenish or livid specks, internally of a whitish or pale yellow. In taste and smell, it is similar to the wood, but weaker: the watery and spirituous extracts are of the same quality, but in less quantity.

The resin, or gum, so called, is brought over in irregular masses, usually friable, of a dusky greenish, and fometimes of a reddish hue; intermixed with small pieces of the wood; of a pungent taste, but of little or no smell, unless heated. It contains more resin than the watery extract made from the wood; and more gummy matter than the spirituous extract. The resin, which is the only active part, is obtained pure both from the gummy substance and from the woody and other indissoluble impurities, by digesting the compound in rectified spirit, drawing off the spirit from the filtered solution till the matter begins to grow thick, and then adding a quantity of water, which will precipitate the pure resin, and keep dissolved such of the gummy parts as the spirit may have taken up. The quantity of resin, thus obtained, amounts commonly to about three fourths of the weight of the gum guaiacum.

Extrattum ligni guaiaci molle & durum.

Guaiacum was first received in Europe as a remedy for the venereal disease; and is said, in the warmer climates, to have been some-times sufficient for subduing it. Though of itself greatly unequal among us to that distem-per, it is a good assistant to mercurial alteratives, and a medicine of great use also in several other cases. To warm and stimulate the habit, to promote the excretions made from the blood, as perspiration and urine, and likewise the grosser evacuations from the intestinal canal, appear to be its primary virtues: in large doses, it operates as a purgative. Where the excretory glands are obstructed, the vessels lax and flaccid, and the habit replete with impure se-rous humours; in sundry cutaneous and ca-tarrhous disorders, some female weaknesses, and chronical rheumatisms; it frequently has good effects. In thin emaciated habits and an acrimonious state of the fluids, it often does harm: in such cases, it has converted a simple itching of the skin to ill-conditioned eruptions, or increased the itching to an almost insupport-able degree: where this happens, nitre, whey, saline laxatives, and warm bathing, are commonly found most effectual for abating the complaints. Hoffman observes that it is, in general, genera, less proper in an advanced age than in other circumstances.

A decoction of half an ounce of the wood or bark may be taken in a day, at proper intervals, the patient keeping warm to promote a diaphoresis. The gum, or extracts made from the wood, are given from a few grains to a scruple or half a dram, and sometimes two scruples; which last dose proves, for the moil part, considerably purgative. The extract: is recommended by Hoffman as an excellent errhine, which occasions a great discharge from the nose, and which he supposes, besides its stimulating power, to be endued with a corroborating one, very friendly to the nervous parts.

Solutions or tinctures of the gum guaiacum are made in the shops, both with rectified spirit of wine, and with the dulcified aromatised volatile alkaline spirits, vulgarly called sal volatile, which in many cases promote its virtues. To six ounces of the gum guaiacum are directed, by the London college, two pints and a quarter of the volatile spirit. The Edinburgh college directs, for the volatile tincture, four ounces of the guaiacum, with two drams of balsam of Peru, and half a dram of essential oil of fafiafras, to be dissolved in a pound and a half of dulcified spirit of sal ammoniac; and for the spirituous solution, one pound of gum guaiacum and three drams of balsam of Peru, with two pounds and a half of rectified spirit. All these are sufficiently elegant solutions of the guaiacum, and the additional articles coincide with its virtue: they may be given from twenty drops to a tea-fpoonful or more in any convenient vehicle. The gum, or resinous extracts, may be dissolved also, by the mediation of thick mucilages, in watery liquors; and in this form are more commodiously taken than in spirituous solutions, the mucilage in great meafure covering the pungency of the guaiacum: the mucilaginous solution, at first greyish or brownish, changes in a few hours to a fine blue or bluish green colour.

Tinct. guai-aci Ph. Lond.

Elixir guai-acin. volat. Ph. Ed.

Elixir guai-acin. Ph. Ed.