By the natives of South America chocolate _nuts_ are used for food, and also as a circulating medium instead of coin: about 1200 of them being considered equal in value to a dollar. A white oily matter, about the consistence of suet, is obtained by bruising these nuts, and boiling the pulp. The oil is by this means liquefied, and rises to the surface, where it is left to cool and congeal, that it may the more easily be separated. This, which is called _butter of cacao_, is without smell, and, when fresh, has a very mild taste. Its principal use is as an ingredient in pomatums. From the nuts, when slightly roasted, an oil is sometimes obtained by pressure, which is occasionally used in medicine. ICOSANDRIA. 207. _The CITRON, LIME, and LEMON, are different varieties of the fruit of a small evergreen shrub, the original or parent stock of which_ (Citrus medica) _was imported from Asia into the southern parts of Europe._ _The_ citron _is oblong, with a very thick rind; the_ lemon _is oblong with a small lump or protuberance at the end; and the_ lime _has no protuberance, has a very thin rind, and is about the size of a small egg. These are the principal marks of discrimination betwixt these fruits, but they are not quite constant._ _The lemon shrub_ (_Fig. 56_) _has large and slightly indented shining leaves, of somewhat oval shape, but pointed; and on the footstalks of the leaves there is no remarkable appendage. The flowers are large and white, but purplish on the outside of the petals._ It is generally supposed that the _citron-tree_ was first introduced from Assyria and Media into Greece, and thence into the Southern parts of Europe, where it is now cultivated to considerable extent. It is also grown in the islands of the West Indies. The fruit, partaking of the same quality as the lemon, with the exception of being somewhat less acid, is seldom eaten raw; but, preserved in sugar as a sweetmeat, it is much used by confectioners and others. The principal consumption of citron is on the Continent, where it is also occasionally employed in medicine. The _lemon-tree_ is a native of Upper Asia, whence, like the citron, it was brought into Greece, and afterwards transplanted into Italy. The _juice_, which is one of the sharpest and most agreeable of all acids, is used in cookery, confectionary, medicine, and in various other ways. By calico-printers it is very extensively employed, as a discharger of colour, to produce, with more clearness and effect, the white figured parts of coloured patterns that are dyed with colours formed from iron. Its juice is procured by simply squeezing the fruit, and straining it through linen or any loose filter; and in Sicily, and other parts of the Mediterranean, it forms an important article of commerce. Being one of the most valuable remedies for the scurvy, with which we are acquainted, it generally constitutes part of the sea store of ships that are destined for long voyages.