1911 Encyclopædia Britannica/Turmeric

TURMERIC (from Fr. terre mèrite, turmeric, Lat. terra merita, deserved, i.e. excellent earth; Skeat suggests that it is a barbarous corruption, perhaps of Arabic karkam, kurkum, saffron or curcuma), the tuberous root of Curcuma longa, L., an herbaceous perennial plant belonging to the natural order Zingiberaceae. It is a native of southern Asia, being cultivated on a large scale both on the mainland and in the islands of the Indian Ocean. Turmeric has been used from a remote period both as a condiment and as a dyestuff, and to a more limited extent as a medicine (now obsolete). In Europe it is employed chiefly as a dye, also as an ingredient in curry powder and as a chemical test for alkalies. The root is prepared by cleaning it and drying it in an oven. There are several varieties (Madras, Bengal, Gopalpur, Java, China and Cochin turmeric), differing chiefly in size and colour and to a slight degree in flavour. Some of these consist exclusively of the ovate central tubers, known as “bulbs,” or ”round turmeric,” and others of the more cylindrical lateral tubers, which are distinguished in trade as “fingers,” or “long turmeric.” Both are hard and tough, but break with a short resinous or waxy fracture, which varies in tint from an orange brown to a deep reddish brown. The colour is due to curcumin, C₁₄H₁₆O₇, of which the drug contains about 0.3%. When pure it forms yellow crystals having a vanilla odour and exhibiting a fine blue colour in reflected light. It is soluble in alcohol, in chloroform and in alkaline solutions, but only sparingly in water. Paper tinged with a tincture of turmeric exhibits on the addition of an alkali a reddish brown tint, which becomes violet on drying. This peculiarity was pointed out by H. A. Vogel in 1815, and since that date turmeric has been utilized as a chemical test for detecting alkalinity. It is of no therapeutic value. In Sierra Leone a kind of turmeric is obtained from a species of Canna.