81. CURCUMA.—TURMERIC. The rhizome of Cur'cuma lon'ga (Linné). Habitat: Southern Asia and East Indies, the best coming from China. Cylindrical pieces (Curcuma longa), about as thick, but not so long, as the finger, tuberculated and somewhat contorted; externally yellowish-gray, internally deep orange-yellow, with a darkish ring marking the circular nucleus sheath; hard, compact, breaking with a glossy, waxy fracture; odor feeble but peculiar; taste aromatic, pungent, bitter.
Curcuma rotunda is round or oval, about the size of a pigeon's egg, or larger, marked externally with annular rings. Both forms of root are derived from the same plant, one being a modification of the other.
CONSTITUENTS.—Volatile oil, a viscid oil, a pungent resin, pasty starch, and a peculiar yellow coloring matter called curcumin, turned brownish by alkalies, becoming violet on drying; with boracic acid it produces an orange tint, changed to blue by alkaline solutions. Stimulant and tonic, but rarely used in that way, except in India, where it is used as a condiment, like ginger. It is used in pharmacy for coloring ointments and tinctures, and for preparing turmeric test-paper.
Preparation of Curcumin.—Obtained pure after removing the oil by exhausting the residual powder with ether, evaporating and recrystallizing from alcohol. Crystals yellow, with a vanilla-like odor.