Cochineal is one of the most valuable substances that are used in dyeing. As imported into this country, it is in the form of a reddish shrivelled grain, covered with a white bloom or powder. The cochineal insects adhere in great numbers, and in an apparently torpid state, to the leaves of the prickly pear. At a certain period of the year they are carefully picked or brushed off, either by a bamboo twig shaped somewhat into the form of a pen, or by an instrument formed of a squirrel's or stag's tail: and so tedious is the operation, that the persons employed in it are sometimes obliged to sit for hours together beside a single plant. In some parts of South America the insects, after being collected in a wooden bowl, are thickly spread upon a flat dish of earthen ware, and cruelly placed alive over a charcoal fire, where they are slowly roasted, till their downy covering disappears, and they are perfectly dried. In other parts they are killed by being thrown into boiling water, by being placed in ovens, or being exposed in heaps to the sun. The quantity of cochineal annually exported from South America is said to be worth more than 500,000l. sterling, a vast sum to arise from so minute an insect; and the present annual consumption of cochineal in England has been estimated at about 150,000 pounds' weight. It is for dyeing scarlet that cochineal is chiefly in demand; but although a peculiarly brilliant dye is now obtained from it, this substance gave only a dull crimson colour until a chemist of the name of Kuster, who, about the middle of the seventeenth century, lived at Bow, near London, discovered the art of preparing it with a solution of tin. Cochineal, if kept in a dry place, may be preserved, without injury, for a great length of time. An instance has been mentioned of some of this dye, 130 years old, having been found to produce the same effect as though it had been perfectly fresh. The attention of the East India Company has, for many years, been directed to the production of cochineal in the East, but hitherto with little success. That which has been brought from India is very small, and greatly inferior to what is imported from New Spain. An imitation of cochineal is made by a preparation of bullock's blood, and some other ingredients. 261. _The SILK-WORM is a smooth and somewhat lead-coloured caterpillar, produced from the eggs of a moth_ (Phalæna mori) _which is found in great abundance in China, the East Indies, the Levant, several parts of Italy, and the South of Spain._