Argol, or Tartar, is a crystalline substance deposited in wine casks during the fermentation of the wine, from the juice of the grape, in which it exists in considerable abundance. It is an impure supertartate of potash; that is, potash combined with a superabundant quantity of tartaric acid. Algol is found in commerce of two colours, white and red. Cream of tartar is the same substance freed from colouring and other extraneous matter.
Blood. See Adrianople red.
Bran acts in some peculiar way on colouring matter, but scarcely on the mordants. It seems to loosen and remove the colouring matter; as also to alter its hue in some cases, an effect obvious in the bran pinks.—Ure.
Chlorine. See Oxymuriatic acid.
Cochineal is the female insect of the coccus cacti found on the cactus coccinellifer and cactus opuntia, Prickly pear or Indian fig, natives of South America, the West Indies, and other tropical regions. The female of the insect is the true cochineal; in her full sized, pregnant, and torpid state, she bears so small a proportion to her former or creeping state, that her antennæ, legs and proboscis are scarcely discernible; her whole appearance is that of a whitish berry, and so it was formerly regarded. This insect is found in a wild state in Mexico, Georgia, South Carolina, and some of the West India Islands, feeding on several species of the cactus; but in some of the Spanish settlements, as well as in Mexico, the insect is domesticated, and fed on the cactus coccinellifer, which is cultivated for the purpose, on which it attains a much larger size than in its wild state. Cochineal is also obtained from the East Indies; but East Indian cochineal has not yet attained the quality of that produced in the West Indies and America. Its use, as a colour for dyeing many shades of red, &c. is great and important.
Copper is also used in dyeing, in the state of a sulphate or blue copperas, a nitrate, and also as an acetate. See Verdigris.
The Gall or Bile of ANIMALS consists of a saponaceous bitter, yellowish fluid, secreted by the liver, and found in the sac usually called the gall-bladder. It is sometimes preferred to soap for cleansing cloths by the dyer and the scourer.
Galls are excrescences produced on the quercus infectoria, a species of oak growing throughout Asia Minor. The gall grows on the shoots of the young boughs, and is produced by an insect, the cynips quercusfolii; this insect punctures the tender shoot with its sting and deposits its egg in the puncture; the egg is soon hatched, and the irritation of the maggot feeding on the plant produces the wen or gall-nut. When the nuts are gathered before the worm within changes to a fly, and not yet having eaten its way out, they are of a dusky green colour, and are called in commerce blue galls, and are by far the best. Those collected after the fly has eaten its way out have a hole in each, are of a whitish yellow colour, considerably lighter than the blue-galls, and of an inferior quality: they are brought to this country chiefly from Aleppo. They are used in large quantities in the arts, principally for dyeing, and making ink. They contain a large quantity of Tannin and Gallic acid.
Indigo is a well known deep blue substance, obtained from the Indigofera tinctoria or Indigo bearing plant, a native of the East Indies, which is propagated by seed and will thrive in most tropical climates; hence we have good indigo from South America, the East Indies, Carolina, &c. The chief criterion of the goodness of indigo is, if, when cut with a knife, it exhibits a reddish copper-like appearance; where this shade is not, or only very slight, the indigo is of inferior value. It is prepared by macerating the leaves in water, whence is obtained the blue feculence or indigo. Indigo is insoluble in water, but soluble in sulphuric acid, hence a solution of it in this acid, forming a sulphate of indigo, is well known in the art of dyeing.
The best indigo is that called Flora, which floats in water, all the other kinds sink in that fluid.