Coccus cacti. Cochineal.

History. — The cochineal insect, Coccus Cacti, belongs to the class Insecta, order Hemiptera ; it is characterized by its depressed, downy, transversely wrinkled body, its purplish abdomen, its short and black legs, and its subulate antennae, which are about one-third of the length of the body. It is found wild in Mexico and the adjoining countries, where it feeds on the different species of Cactus and the allied genera, but especially the Opuntia Cochenillifera, on which it thrives best. They are collected at various seasons. The best are the product of the first collection, which consists of the impregnated females ; the males are not collected. Those killed by the heat of a stove, are said to be superior to those destroyed by boiling water. As obtained in the shops, Cochineal is in irregularly-circular or oval, somewhat angular grains, about one-eighth of an inch in diameter, convex on one side, concave or flat on the other, and marked with several transverse wrinkles. There are two varieties, one of a reddish-gray color, silver grains, the other almost black, black grains ; there is no difference in their quality.

The Silver Cochineal is said to consist of the female insect killed before it has laid its eggs ; Black Cochineal, of the female after having laid its eggs ; the first is the most esteemed. There is also an inferior sort, consisting chiefly of young insects, called Granilla.

Cochineal has a faint heavy odor, and a bitter, slightly acidulous taste ; its powder is of a purplish-carmine color. It consists of carmine, animal matter, stearin, olein, etc. The coloring matter of cochineal is dissolved out by water, alcohol, and proof spirit.

Carmine may be prepared by boiling one pound of powdered cochineal and three drachms and a half of subcarbonate of potassa, in a boiler containing seven gallons of water. After boiling for a few minutes, take the boiler off the fire, and place it on a table, inclined to one side so as to facilitate decantation. Add powdered alum, eight drachms, and stir the solution. The liquor changes color and assumes a more brilliant tint. After a quarter of an hour, the cochineal will have deposited, and the liquor have become as clear as if it had been filtered. It contains the carmine in suspension. The liquor is then decanted into a similar pan, and placed on the fire, adding three drachms and a half of isinglass, which has been previously dissolved in two quarts of water and strained. At the moment of ebullition the carmine rises to the surface, and a coagulum forms as in clarification with white of egg. The pan is then removed from the fire, and the liquor stirred with a spatula. After a quarter of an hour the carmine will be deposited, when the liquor is to be decanted, and the deposit drained on a strained filter, and then dried in a stove at a temperature from 82° to 86°. If dried in the open air it will become moldy. This makes a very fine carmine. The remaining solution will make fine carminated lake. A fine red ink may be made as follows : Take of cochineal in powder eight scruples, carbonate of potassa sixteen scruples, distilled water eight fluidounces, mix together and boil ; then add of alum four scruples, bitartrate of potassa two ounces; let them stand for twenty-four hours, filter, and add of powdered gum Arabic half an ounce.

Properties and Uses. — Anodyne. Used in hooping-cough, and neuralgic affections. Also used to color tinctures and ointments. Dose, from five to ten grains, three or four times a day.

Off. Prep. — Tinctura Cardamomi Composita.

The American Eclectic Dispensatory, 1854, was written by John King, M. D.