Turmeric, a name of unknown origin, given to the rootstocks of several species of curcuma (Pers. IcurJcum, the name also for saffron, and applied to this because of its similarly yellow color), especially to C. longa, plants of the ginger family, which some botanists include in the scitaminece or banana family. The plants are indigenous to southern Asia, and are cultivated in various eastern countries. They have perennial, palmately divided, tuber-like rootstocks, and annual stems; the large lanceolate leaves are radical, and from among them rises a short stem, bearing a thick spike, from between the bracteal scales of which the flowers appear in succession, much as in the related ginger and arrowroot, figured under their titles. In commerce the rhizomes are called roots, and are distinguished as long and round, though both are produced by the same plant, and are also known by the names of the localities of export, each of which has its long and round kinds. Long turmeric is about the size of the little finger, 2 or 3 in. long, curved, and tuberculated from a tendency to branch; the round is more usually oval, an inch thick and 2 in. long; both kinds are marked by transverse scars or wrinkles, are yellowish externally, and internally orange-yellow or reddish brown; they have an odor like that of ginger, but peculiar, and a warm aromatic taste, and when chewed tinge the saliva yellow; they form an orange-yellow powder, the condition in which they are generally kept in the shops.
The drug contains about one per cent, of an essential oil, and a peculiar coloring matter, curcumine, which is crystallizable, almost insoluble in water, but very soluble in alcohol and ether. Turmeric was formerly employed in medicine as an aromatic tonic, but its use is now solely to color ointments, tinctures, and other preparations. Though the color is fugitive, it is considerably used in dyeing; it gives a fine yellow upon silk, and is used as the basis of some greens, and upon woollens to produce some shades of brown. It forms an important ingredient in curry powder (see Curry), and is much used to color varnishes (see Lacquer). The changes produced in curcumine by alkalies and other chemical agents make it available as a test; turmeric paper, made by staining paper with a tincture of the root, is often employed in the laboratory as a useful though not very accurate test, as one acid at least produces a reaction similar to that of the alkalies. Turmeric paper touched with an alkaline solution changes from yellow to brownish red, becoming violet on drying; boracic acid produces a similar change, but the tint is orange, and when an alkali is added it turns to blue.
Turmeric, Long and Bound.