532 ANIMAL SUBSTANCES 



COCHINEAL 



(Coccus) 



Source, &C. Commercial cochineal is the dried, fecundated, female 

 insect, Coccus cacti, Linne (Phylum Arthropoda, Class Insecta, Order 

 Hemiptera). 



The cochineal insects are indigenous to Central America and Mexico, 

 where they live upon the fleshy branches of various species of Nopalea 

 (Cactacece). The production of aniline dyes has, however, largely 

 diminished the trade in cochineal, and at the present time the insects 

 bred in the Canary Islands form the bulk of the commercial drug. 



The insects are of a bluish red colour and very minute, measuring 

 about a millimetre in length, and the male alone is provided with 

 wings. After fecundation the female insects rapidly increase in size 

 and develop abundance of a red colouring matter. They are then 

 brushed off the plants and killed either by the fumes of burning sulphur 

 or charcoal, or by hot water or stove heat. They are then dried in 

 the sun (during which process they shrivel to about one- third of their 

 size) and sifted to remove foreign fragments, &c. The number of 

 harvests varies with the climate ; in the Canary Islands there are 

 generally two. 



Description. The dried cochineal insects of commerce are about 

 5 mm. long, oval in outline, flattish or slightly concave on one side 

 and arched on the other. They are transversely wrinkled and a 

 purplish black or greyish white colour, according to the variety (see 

 below). They scarcely show any resemblance to insects, but when 

 macerated in water they swell considerably, and then the three pairs 

 of legs can be discerned. They are brittle, and easily reduced to a 

 dark red or puce-coloured powder. 



Constituents. Cochineal contains up to 10 per cent, of a red 

 colouring matter, carminic acid, which is obtainable in small, red 

 prismatic crystals ; it is soluble in water, alcohol, and in alkaline 

 solutions. The drug also contains fat (about 10 per cent, and wax 

 (about 2 per cent.), together with albuminoids, inorganic matter, &c. 



The exact methods by which commercial carmine is produced are 

 trade secrets ; the preparation contains about 15 per cent, of water, 

 50 per cent, of carminic acid, 7 per cent, of ash, and about 20 per cent, 

 of nitrogenous substances. It appears to be produced by precipitating 

 infusions of cochineal by alum, in the presence of lime salts and either 

 albumen or gelatin. 



Varieties. Two chief varieties of cochineal are recognised, viz. 

 black grain and silver grain ; the former are of a uniform purplish 

 black colour, the latter greyish white. The greyish white colour of 



