Coccus. Cochineal. Coccus Cacti. The female Cochineal insect dried; reared in Mexico and Teneriffe.

Description. Of an oval form, convex on one side, flat and slightly concave on the other, about two lines long, wrinkled. One variety is of a reddish-gray colour, due to the presence of a white powder upon the red surface; this powder when examined by the microscope, has the appearance of fine wool; the other, nearly black, and having but little of the white powder. The female insects are alone preserved; they are procured by brushing them off into bags, and killing them by immersion in hot water. The difference in the two varieties, the silver and the black grains, consists in this; the silver is made up of the impregnated female just before she has hatched her eggs; the black, of the insect after the eggs have been laid and hatched. Cochineal yields when crushed a puce-coloured powder. The gray insect becomes black when warmed before the fire.

Prop. & Comp. Cochineal consists of fatty matters, salts, etc., and a peculiar colouring matter called carmine; it occurs in the form of small grains of a purple-red colour, soluble in water and alcohol. Acids increase the red colour, while alkalies render it violet. The colouring matter of carmine has been found to have acid properties, and has been called Carminic acid (C28 H14O16).

Off. Prep. Tinctura Cocci. Tincture of Cochineal. [Not officinal in U. S. P.] (Cochineal, in powder, two ounces and a half; proof spirit, twenty fluid ounces. Prepared by maceration.)

Therapeutics. Chiefly used as a colouring matter, much employed in the arts as a dye; it was formerly much esteemed in the treatment of pertussis.

Dose. Of the tincture, 30 min. to 1 1/2 fl. drm.

Adulteration. Inferior cochineal is sometimes covered with some white powder, as talc, sulphate of baryta, or carbonate of lead, to give it the appearance of the finer variety; also with bone black, to give it the black colour.