205. _INDIGO is a blue dye prepared from a plant_ (Indigofera tinctoria) _with a shrubby stem, oblong, smooth, and winged leaves, bunches of flowers shorter than the leaves, and cylindrical pods slightly curved, which grows in America and the West Indies._ The culture of indigo is an object of considerable importance in the West Indian islands, and in some parts of America. The grounds appropriated to it are sown about the middle of March, in rows fifteen inches asunder. The plants come into flower about three months afterwards, and are in a state to be cut about the month of August. They are cut with a kind of reaping hook, a few inches above the root. The plants are then laid in strata, in a vat or cistern constructed of strong mason-work, and so much water is poured in as will cover them. In this state they are left to ferment, and the fluid or pulp, which is first green, afterwards becomes of deep blue colour. It is now drawn off into another vat, where it is strongly and incessantly beaten and agitated, until the colouring matter is united into a body. The water is then let off by cocks in the sides of the vat; and the indigo, after undergoing some further preparations, is cast, in boxes or moulds, into small pieces, each about an inch square, and packed up for sale. The vapour which issues from the fermented liquor is extremely injurious to the negroes who attend the process; and as peculiar attention is requisite both to this and the granulating of the pulp, many indigo-planters have failed in the manufacture of this article. Indigo is employed by dyers, calico-printers, and paper-stainers, to an extent so great that nearly 500,000 pounds' weight of it are annually imported into this kingdom. The _stone-blue_ used by laundresses, and the colours called _Saxon-blue_, and _green_, are made from indigo. Painters use it as a water-colour. This article is frequently adulterated with earth, ashes, and pounded slate. The genuine drug ought to be of rich, dark blue colour, approaching to black; and, when broken, should display the lustre of copper. It ought not to sink in water, nor to leave any sediment when dissolved. ---- CLASS XVIII.--POLYADELPHIA. ---- DECANDRIA. 206. _CHOCOLATE is a kind of cake or hard paste, sometimes made of different ingredients, but the basis of which is the pulp of the cacao or chocolate nut, a produce of the West Indies and America._ _The chocolate tree_ (Theobroma cacao, Fig. 54,) _both in size and shape, somewhat resembles a young cherry tree, but it separates near the ground into four or five stems. The leaves are each about four inches in length, smooth but not glossy, and of dull green colour. The flowers are saffron-coloured, and very beautiful._