GUAIACUM, (Neo-Lat., from Sp.
guayaco, guayacan). A genus of trees of the natural order Zygophyllere, natives of the trop ical parts of America, which have abruptly pin nate leaves, and axillary flowers on one-flowered stalks, often in small clusters. The trees are remarkable for the hardness and heaviness of their wood, generally known as lignum vita!, but also as guaiacum wood, and sometimes as Brazil wood; as well as for their peculiar res inous product, guaiacum, often but incorrectly called gum guaiacum. The species to which the commercial lignum vitae and guaiacum are com monly referred are Guaiacum officinale and Guaiacum sanctum, natives of the West India Islands, and of some of the continental parts of America. Guaiacum officinale is a tree some times 60 feet high, with two or three pairs of ovate, obtuse, and perfectly smooth leaflets, pale blue flowers, a furrowed bark, and generally a crooked stem and knotted branches. Some spe cies have been grown as ornamentals in Florida and southern California. It seems probable that other species supply part of the guaiacum wood and resin of commerce. At present the supplies are obtained chiefly from Cuba, Jamaica, and San Domingo. The wood is exported in billets about three feet long and one foot in diameter, of a greenish-brown color. This is the color of the heart-wood; the sap-wood is pale yellow. Guaia cum wood sinks in water, and is remarkable for the direction of its fibres, each layer of which crosses the preceding diagonally; annual rings are scarcely to be observed, and the pith is ex tremely small. It is much valued, chiefly by
turners. Ship's blocks, rulers, pestles, and bowls (q.v.) are among the articles most commonly made of it. When rubbed or heated it emits a faint disagreeable aromatic smell; its taste is also pungent and aromatic. Shavings and rasp ings of the wood are bought by apothecaries for medicinal use. The bark is also used in medi cine on the Continent of Europe, but not in Great Britain or America. The virtues of both wood and bark depend chiefly on the resin which they contain, and which is itself used in powder, pill, and tincture. It is an acrid stimulant, and has been employed with advantage in chronic rheu matism, skin diseases, and catarrh. It has also been highly praised as a preventive of gout. In the sixteenth and seventeenth centuries guaiacum was the remedy most in repute for syphilis. The resin sometimes flows spontaneously from the stem of the guaiacum-tree; it is sometimes ob tained artificially. It is of a greenish-brown color, and has a brilliant resinous fracture. It has scarcely any taste, but leaves a burning sen sation in the mouth. One of its most striking characteristics is that it is colored blue by its oxidizing agents. It contains guaiacic acid, which closely resembles benzoic acid, and yields on dis tillation certain definite compounds known as guaiacin, pyroguaiacin, and guaiacol.