This section is from the book "Meals Medicinal", by W. T. Fernie. Also available from Amazon: Meals Medicinal: With "Herbal Simples" Curative Foods From the Cook in Place of Drugs From the Chemist.
A rich crimson dye is frequently used for kitchen purposes, being altogether harmless, as obtained from the Cochineal insect, dried, powdered, and infused, or made into a liquid essence. This diminutive, silvery-looking kermes, or insect, of West Indian origin, often supposed by mistake to be a small seed, is in reality the parched, glistening carcase of the Coccus Cacti, so called because making the Nobal Cactus its habitat. The insects are found thus in Mexico, New Grenada, and the Grand Canary, where the peasants who manage the nobaleries sweep the same three times in the year with the edge of a feather from the broad lobes of this cactus, or "prickly pear".
The diminutive bugs elaborate carmine within themselves; but only the females are of service for this duty, chiefly whilst remaining unpaired. They are swept into bags of muslin, and plunged into boiling water, being afterwards dried in the sun, and packed in convenient parcels; when examined in this state they closely resemble the striped seeds which hang on our "ladygrass" of the fields. The colouring principle of the Cochineal insect is carminic acid. When infused in water, and pressed, the tiny bodies exude a liquid of the purest ruby tint, perfect and superb; but the dye taken from the second, and third sweepings of the Cactus is styled in the trade "black Cochineal,"and is not worth more than one-fifth of the maiden product. Sir Edward Arnold, in stating lately that the insects fill themselves with ruby red liquid from the lobes, and fruit of the Nobal Cactus, was mistaken, seeing that its juices are colourless; and at Kew the director of the Cactus House represents his lack of acquaintance with any Cactus - Nobal, or other - which yields a coloured juice.
Curatively the Cochineal has long been a popular remedy for whooping cough, and it would seem that this confidence is justified by facts. Austrian experimentalists have found that large doses of the Cochineal dye will provoke a violent cough, occurring with spasmodic seizures, and with the characteristic in-drawing "whoop " of the breath; whilst much smaller doses afford singular relief to this distressing trouble when it attacks as epidemic whooping cough. The Cochineal insect also contains, besides fat, and carmine, a principle known as "tyrosin" which specifically affects the kidneys; whereby the medicament in much-reduced doses has effectually relieved cases of Bright's disease, and kidney-colic, or congestion. The carmine is found in combination with phosphate, and carbonate of lime, muriate, and phosphate of potash, and stearine (the basis of wax candles). Rouge powder, used both on, and off the stage for giving a roseate complexion to the cheeks, is made by mixing half a pound of prepared chalk with two ounces of freshly-prepared carmine.