3 Spec. Plant Willd. ii. 538.

Cl. 10. Ord. 1. Decandria Monogynia. Nat. ord. Zygophylleae.

G. 819. Calyx five parted, unequal. Petals five, inserted into the calyx. Capsule angular, three or five celled.

Species 2. G. officinale. Officinal Guaiacum. Med. Pot. 3d ed. 557. t. 200.

Officinal. Guaiaci lignum et resina, Lond. Guaiaci officinalis LIGNUM-RESINA, Edhl. GuAIACUM OFFICINALE; LIGNUM, resina, Dub. The wood and resin of Guaiacum.

Syn. Gayac, Gomme-resin de Gayac (F.), Gemeiner Franzosenholz, Guajak-gummi (G.), Pokhout (Dutch), Franzos trace (Dan.), Franzosenholts (Swed.), Guajaco, Gommo-resina di Guajaco (I.), Guayaco (S.), Guajaco (Port.).

This tree is a native of Jamaica, Hispaniola, and the warmer parts of America.4 It rises forty feet in height, and is four or five in circumference, with many divided knotted branches. The bark of the trunk is of a dark grey colour, variegated with greenish or purplish specks, but that of the branches is ash-coloured, with fissures. The leaves are abruptly pinnate, consisting of two or three pairs of smooth, shining, veined, obovate, dark green leaflets, almost sessile. The flowers are peduncled in a kind of umbels, which spring from the divisions of the smaller branches. The calyx consists of five concave, oblong, blunt, spreading, unequal, deciduous leaves; the petals are five, of a rich blue colour, elliptical, concave, and spreading; the stamens are erect and villous, with yellowish hooked anthers: the germen is oval, with a short style and simple stigma; and the capsule sub-turbinate, on a short pedicel, smooth, and of a pale ferruginous hue, pentagonous, with ribbed angles, and five-celled: but two or three of the cells are often abortive.5 The seeds are solitary and angled.

All the parts of this tree possess medicinal qualities; but the wood and the peculiar substance afforded by it are the only parts used : the virtues of the wood depend altogether on the peculiar matter it contains. This is spontaneously exuded from the tree, and is called native gum : it concretes in tears, which are semipellucid and very pure; but the greater part of it is obtained by making incisions into the trunk, or, as it is termed, jagging the tree. This operation is performed in May: and the juice, which flows copiously, is concreted by the sun. It is also obtained by sawing the wood into billets, and boring a hole longitudinally through them; so that, when one end of a billet is laid on a fire, the guaiac, melting, runs through the hole from the opposite end, and is collected in a calabash. Boiling the chips or raspings in salt and water, also separates the guaiac, which, as it rises to the surface, may be collected by skimming.

1 Hufeland uber die Natur, §c. der Scrofula. Kostrewski, Dissert, de Gratiola, p. 64. The Spanish name, Guayaco, is derived from the Caribhee.-Humboldt.

4 The tree was cultivated in this country by the Duchess of Beaufort, 1699.

5 Gaert. de Fructibus, ii. 148. t. 113. fig. 1.

The wood is brought to this country either in large solid pieces, which weigh from four to five cwt. each, and are covered with a yellowish alburnum; or it is already rasped. The guaiac, or gum, as it is improperly termed, arrives in casks and mats: the former containing from one to four cwt., the latter generally less than one cwt. each.

Qualities.-The wood of guaiacum is inodorous, but when heated it emits an aromatic odour; and the taste is bitterish, subacrid, and biting. It is very hard, heavier than water; its sp. gr. 1.333; it is externally yellowish, and internally of a blackish brown colour mixed with green streaks. Its goodness may be ascertained by exposing its raspings to the fumes of nitrous acid, which give it a bluish-green colour, if it be good: yet the decoction is not affected by nitrous acid. The resin, or guaiac, has a fragrant odour, with scarcely any taste, but occasions, when swallowed, a sensation of heat in the throat. It has a resinous aspect; is of a greenish brown colour externally, and internally presents a mixture of greenish, reddish, and brownish tints. It is somewhat translucent, breaks with a vitreous fracture, and is easily reduced to a powder, which is grey at first, but becomes green in a short time when it is exposed to the air and light; a change which appears to depend on the absorption of oxygen.1 The specific gravity of guaiac is 1.2289. It was generally regarded as a gum resin, till Mr. Brande's experiments showed it to be a substance sui generis, differing from both gum and resin.

When guaiac is digested in water a little extractive only is dissolved, in the proportion of 9 parts in 100, and the infusion has a greenish brown colour and a sweetish taste. Alcohol dissolves readily 95 parts in 100, and the solutionis decomposed by the mineral acids, affording precipitates which assume various tints of colour. (See Tinctura Guaiaci.) Sulphuric ether dissolves four parts in ten of guaiac, and when the solution is evaporated on water, it leaves a tough, pellucid, pale brown pellicle, which appears to be pure guaiac. It becomes green after some time; and a small portion of extractive remains dissolved in the water. The alkaline solutions and their carbonates dissolve it readily; and the solutions are precipitated by the diluted sulphuric, the nitric, and the hydrochloric acids. Sulphuric acid dissolves it with scarcely any effervescence; affording a solution of a rich claret-colour, which, when fresh prepared, deposits a lilac-coloured precipitate on the addition of water; and when heated, separates some charcoal Nitric acid dissolves it with a strong effervescence and a copious extrication of nitrous fumes; and when the solution is evaporated, it yields a large portion of oxalic acid. The diluted acid converts it into a brown resinous substance.

Hrdrochloric acid dissolves a small portion only, and affords a solution of a brown colour. I found that, during the solution of guaiac in these acids, the heat which was evolved raised the thermometer in the following proportions: in the sulphuric, 44; in the nitric, 120; and in the hydrochloric, 8 degrees. Nothing comes from the distillation of guaiac in water; but Mr. Brande obtained from 100 parts of it distilled per se in close vessels, the following products: acidulous water 5.5, thick brown oil 24.5, thin empyreumatic oil 30.0, charcoal remaining in the retort 30.5, and 9.5 of gases, which were chiefly carbonic acid and carbureted hydrogen.1 From these experiments it is clear that guaiac differs from resin; and we also learn that the mineral acids are incompatible in prescriptions with it.

1 This effect of light and air was first noticed by Dr. Wollaston, who found that the most refrangible produced this change; and subsequent experiments of Mr. Brande clearly proved it to arise from oxygen. I found that the change takes place in an hour, when the powder is exposed to sunshine. It appears to be again deoxidized if exposed to the least refrangible rays only, according to Dr. Wollaston's experiments.

It is sometimes adulterated with common resin and man-chinal gum. The former is detected by the turpentine emitted when the suspected guaiac is thrown on hot coals; and the latter, by adding to the alcoholic solution a few drops of sweet spirit of nitre, and diluting with water, the guaiac is precipitated, but the adulteration floats in white striae.

Medical properties and uses.-Both the wood and the guaiac are stimulant, diaphoretic, diuretic, and purgative. The wood was introduced into Europe by the Spaniards, as a remedy for lues venerea, in 1508, by Gonsalvo Farrand, and gained much celebrity from curing Ulrich Van Hutten; but it had long before been used for the same purpose by the natives of St. Domingo : and it is not certain that Van Hutten's case was one of pure syphilis, as he had been suffering from the disease from the age of nine years. It obtained so much reputation, however, that the exhibition of mercury was discontinued for a considerable length of time1; and even in the eighteenth century its specific powers over this disease were maintained by Boerhaave: but frequent disappointments and more correct observations have shown that it possesses no powers of eradicating the venereal virus; and that it is useful only after a successful mercurial course, for repairing the strength and vigour of the system; "and where a thickened state of the ligaments, or of the periosteum, remains, or where there are foul indolent ulcers2;" or in suspending the progress of some of the secondary symptoms for a short time, as ulcers of the tonsils, eruptions, and nodes.

The decoction of the wood has been found more useful in cutaneous diseases, scrofulous affections of the membranes and ligaments, and in ozcena. The guaiac itself is an efficacious remedy in chronic rheumatism and arthritic affections 3, as well as those diseases for which the decoction of the wood is usually given; and in every respect it may be regarded as the active ingredient of the wood. Its sensible effects are a grateful sense of warmth in the stomach, dryness of the mouth, and thirst, with a copious flow of sweat, if the body be kept externally warm, or if the guaiac be united with opium and antimonials: but when the body is freely exposed to cool air, instead of producing diaphoresis, it augments considerably the secretion of urine. It may be exhibited either in substance or in tincture. The dose is from grs. x. to 3 ss., in the form of pills or of bolus; or made into an emulsion with water by means of mucilage or yolk of egg. Larger doses purge.

1 Philosophical Trans. 1806, and Phil. Mag. xxv. 107.

Officinal preparations. Of the wood -Decoctum Guaiaci comp., E.D. Of the Guaiac:-Mistura Guaiaci, L. Tinc-tura Guaiaci, L. E. D. Decoctum Sarsaparillae comp., L. D. Tinctura Guaiaci composita, L. E. D. Pulvis Aloes comp., L.D.

1 It was then sold for seven gold crowns a pound.

2 Pearson's Observations on the Effects of various Articles of the Materia Medica in the Cure of Lues Venerea, p. 10.

3 The Chelsea Pensioner, a nostrum by which Lord Amherst was cured of rheumatism, is composed of Guaiac 3j., Pulp. Rhei 3ij., Supertart. Potassae j., Sulph. ij., Nucis myrist. j. in pulv. trit. et per opem mellis misce ut fiat Electu-arium. Two large spoonsful to be taken night and morning. Jesuit Drops also consist of Guaiacum, Balsam of Copaiba, and Oil of Sassafras, made into a tincture by spirit-Pharmacologia, p. 237.