LOGWOOD (so called because imported in logs). The dark red solid heart-wood of Ihema toxylon campeehianum. The tree belongs to the natural order Leguminosx, and grows in Mexico and Central America, and in some of the West India islands. It is the only known species of its genus. It grows to a height of 20 to 50 feet; the leaves are pari-pinnate; the racemes many flowered, and longer than the leaves. The sap wood is yellowish, and. being worthless, is hewn off with the bark. The heart-wood is heavier than water, closc-grained, but rather coarse. It has a slight smell resembling that of violets, a sweetish taste. is astringent, and contains a dis tinguishing crystalline principle, called btrma toxylin (q.v.). Logwood is imported in billets or logs, usually of very irregular shape; the color is a dark blood-red, becoming almost black after long exposure. The infusion of the wood is also blood-red, which color it yields readily to boiling water; it is changed to light red by acids, and to dark purple by alkalies. While all other dye woods have been nearly superseded by the arti ficial colors made from coal-tar, logwood is still used in large quantities, mainly for the produc tion of blacks, but also as a substitute for indigo in the production of blue. It is further used in
the manufacture of ink, and it is employed to some extent in medicine for controlling all forms of diarrhea. In dyeing it is used either in the form of chips or in the form of extracts. Since Inematoxylin, the ingredient of logwood, to which its value as a dyewood is due, is not in itself a coloring matter, but is capable of yielding one under appropriate treatment, the wood- must be subjected to a process of 'curing.' This may he effected by simply moistening the chips and ex posing them to the action of the air; usually. however, glue and various chemicals are added for the purpose of hastening the operation. though it is by no means certain that those sub stances have a beneficial effect. Of the varieties of logwood that occur in commerce, Campeachy logwood is considered the best and commands a considerably higher price than the other varie ties. See DYEING.