1902 Encyclopedia > Cochineal

Cochineal




COCHINEAL, a dye-stuff used for the production of scarlet, crimson, orange, and other tints, and for the preparation of lake and carmine. It consists of the females of Coccus cacti, an insect of the order Hemiptera, which feeds upon various species of the Cactacece, more especi-ally the nopal plant, Opuntia coccinellifera, a native of Mexico and Peru. The dye was introduced into Europe from Mexico, where it had been in use long before the entrance of the Spaniards in the year 1518, and where it formed one of the staple tributes to the Crown for certain districts, In 1523 Cortes received instructions from the Spanish court to procure it in as large quantities as possible. It appears not to have been known in Italy so late as the year 1548, though the art of dyeing then flourished there. Cornelius van Drebbel, at Alkmaar, first employed cochineal for the production of scarlet in 1650. Until about 1725 the belief was very prevalent that cochineal was the seed of a plant, but Dr Lister in 1672 conjectured it to be a kind of kermes, and in 1703 Leeu-wenhoeck ascertained its true nature by aid of the micro-scope. Since its introduction cochineal has supplanted kermes (Coccus ilicis) over the greater part of Europe. The male of the cochineal insect is half the size of the female, and, unlike it, is devoid of nutritive apparatus ; it has long white wings, and a body of a deep red colour, terminated by two diverging setae. The female is apterous, and has a dark-brown plano-convex body ; it is found in the proportion of 150 to 200 to one of the male insect. The dead body of the mother insect serves as a protection for the eggs until they are hatched. Cochineal is now furnished not only by Mexico and Peru, but also by Algiers and the S. of Spain. In Teneriffe it was success-fully cultivated in 1858, on the failure of the vines there through disease, but the diminished value of cochineal of late years has much affected its production in the Canaries, Cochineal is collected thrice in the seven months of the season. The insects are carefully brushed from the branches of the cactus into bags, and are then killed by immersion in hot water, or by exposure to the sun, steam, or the heat of an oven—much of the variety of appear-ance in the commercial article being caused by the mode of treatment. The dried insect has the form of irregular, fluted, and concave grains, which weigh about 3^ of a grain, as many as 70,000 insects being estimated to weigh 1 lb. Cochineal has a musty and bitterish taste, There are two principal varieties—silver cochineal, which has a greyish-red colour, and the furrows of the body covered with a white bloom or fine down, and black cochineal, which is of a dark reddish-brown, and destitute of bloom. Granilla is an inferior kind, gathered from uncultivated plants. The best crop is the first of the season, which consists of the unimpregnated females ; the later crops contain an admixture of young insects and skins, which contain proportionally little colouring matter.
Cochineal owes its tinctorial power to the presence of a substance termed cochinealin, or carminic acid, a compound of hydrogen, carbon, and oxygen, which may be prepared from the aqueous decoction of cochineal. The comparative value of different specimens of cochineal may be ascertained by a method based upon the bleaching action of ferricyanide of potassium upon a weak potash solution of the dye. The black variety of cochineal is sometimes sold for silver cochineal by shaking it with powdered talc, or heavy-spar; but these adulterations can be readily detected by means of a lens. The duty on cochineal was repealed in 1845. In 1869 the exports of cochineal from the Canaries reached 6,310,000 lb, value £842,921. Of this amount 4,232,600 tt>, consisting of grama, granilla, and polro, were shipped to Great Britain, value £554,092. More than half of this quantity was supplied by the Island of Grand Canary. In three months ending 31st March 1876 the imports were 10,094 cwts, value £112,534.

For a monograph of the Coccidas, including the cochineal insect, see Signoret, Ann. Soc. Enl. France, 1868-74. For accounts of the cochineal insect consult also—Theis, ibid., v. p. 1 ; Bunneister, Handbuch der Entomologie; Vincent, Ann. Sci. Nat., vol. viii., 1st ser.; Westwood, Modem Classification of Insects, pp. 448, 449. For a description of the cultivation of cochineal in Java, see Vcth's Woordenboek van Nederlandsch Indie—Cochenille. See also " Ob-servations on the Making of Cochineal in Jamaica," in Phil. Tran., 1691, pp. 502-3 ; and Boyle's Essay on the Productive Resources of India, pp. 47-65, 1840.








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