Guaiaci Lignum. Guaiacum, or Guaiac Wood. Lignum Vitas. The Wood of Guaiacum Officinale, the Officinal Guaiacum Tree; a native of St. Domingo and Jamaica; in the form of shavings or raspings.

Guaiacum. [Guaiaci Resina. U. S.] Guaiacum Resin. A resin obtained from the stem of Guaiacum officinale by natural exudation from incisions, or by heat.

Description. Guaiacum wood is met with in large logs, and known by the name of Lignum Vitoe, generally denuded of bark, and consisting of the duramen or heart-wood, of a dark greenish-brown colour, and the alburnum of a yellow tint; it is very hard, tough, and heavy; sp. gr. 1.33; the heart-wood contains a large amount of the guaiacum resin, which is dark brown, transparent, in very thin layers, brittle, of aromatic odour, and leaving, when tasted, a peculiar burning sensation in the throat; the tears are oval, of varying size, and often covered with a greenish powder on the surface. The resin is usually procured by boring a longitudinal hole in the log, and putting one end of it into the fire; the resin melts and exudes at the other end, where it is collected. That obtained by natural exudation is in the form of tears of varying size. The wood is commonly sold in chips or raspings for medicinal purposes; these when boiled in salt water yield the resin, which rises to the surface.

Prop. & Comp. The most important constituent of the wood is the above-described resin, which has a sp. gr. 1.29, is insoluble in water, or yields to that fluid only some extractive matter mixed with it; a solution in rectified spirit strikes a clear blue colour when applied to the inner surface of a paring of raw potatoe, due to the action of guaiacic acid on the gluten; soluble in alcohol and ether, also in alkaline solutions; precipitated from alcohol by water, and from alkalies by acids; acted on by nitric acid and chlorine, when the colour is first shaded green, then blue, at last brown. The resin contains guaiacic acid, which has the composition (HO, C12 H7 O5), and has been obtained in crystalline needles, and another resinous acid the composition of which is not well known.

Off. Prep. - Of the Resin.

Mistura Guaiaci. Mixture of Guaiacum. [Not officinal in U. S. P.] (Powdered guaiacum, half an ounce; sugar, half an ounce; gum-arabic, powdered, a quarter of an ounce; cinnamon water, one pint.)

[Tinctura Guaiaci. Tincture of Guaiac, U. S. Two pints of tincture are obtained by percolation through six ounces of Guaiac]

Tinctura Guaiaci Ammoniata. Ammoniated Tincture of Guaiacum. (Guaiac resin in fine powder, four ounces; aromatic spirits of ammonia, one pint.)

[Guaiac, in moderately coarse powder, six troy ounces; aromatic spirits of ammonia, two pints; macerate for seven days and filter. U.S.]

Guaiacum resin also enters into the composition of pilula calo-melanos composita.

Guaiacum wood forms an ingredient of decoctum sarsae composi-tum.

Therapeutics. Guaiacum, either in the form of wood or resin, when taken internally, is apt to cause heat in the throat, irritation of the intestinal canal, and, in large doses, purging. When absorbed it acts as a stimulant, diaphoretic and alterative, and is by some considered to be an emmenagogue. It is employed in chronic forms of rheumatism, especially that variety called cold rheumatism, in which the symptoms are relieved by warmth; also in periosteal affections connected with a syphilitic taint, and other chronic affections, as gout, skin diseases, and dysmenorrhoea.

Dose. Of guaiac resin, 10 gr. to 30 gr.; of mistura guaiaci, 1 fl. oz. to 1 1/2 fl. oz.; of tinctura guaiaci ammoniata, 1/2 fl. drm. to 1 fl. drm.; of tinctura guaiaci 1 fl. drm. to 2 fl. drm.

Adulteration. Other resins, as that from the coniferous trees, detected by the terebinthinate odour, and solubility in oil of turpentine. A simple tincture of guaiacum, when thrown into water, becomes milky, from the precipitation of the resin: if a solution of potash is now carefully added, it is cleared, and remains so after excess of the alkali, provided guaiacum only be present, but not if other resins are contained in the tincture. The presence of guaiacum resin can be shown by the potatoe test given above.