Cocoa, a preparation of the seeds of the tree called by Linnaeus thedbroma cacao. (See Cacao.) Several varieties of the tree have been since described, which produce beans, or seeds, varying somewhat in their size and properties. Their use is for the manufacture of chocolate. The article was unknown in Europe till it was introduced from Mexico in 1520 by the Spaniards; with them its preparation was long afterward kept secret. The seeds are prepared for use by roasting in the same way as coffee is roasted. When the aroma is well developed, the beans are turned out into shallow wooden vessels and stirred till cool. Those which have been fermented now lose the shells readily, and split open into several lobes like split beans. The shells, amounting to about 12 per cent, of the whole weight, are separated by winnowing, and form an inferior quality of cocoa known as shells. The split seeds thus prepared may be used for food by long boiling; but for making chocolate they are ground, and mixed with other substances. (See Chocolate.) Their average composition, according to Johnston, is nearly as follows: water, 5 per cent.; starch, gum, etc, 22; gluten, etc, 20; oil, 51; theobromine, 2. The theobromine is a white, crystallizable substance, similar to the theine in tea, but contains more nitrogen.

The other constituents, as starch, gum, gluten, and the large proportion of fat, give to cocoa the variety of nutritive qualities possessed by milk, and like this it contains every ingredient necessary to the growth and sustenance of the body. A volatile aromatic oil and a bitter and an astringent principle are present, which affect the taste and qualities of the cocoa, though they are not detected in the analyses. The former is developed in the roasting, and is the cause of the aroma which is then exhaled. The fatty oil, called cocoa butter, resembles tallow in whiteness and consistence; it melts at 122° F., and in this condition may be separated by expressing it from the other ingredients. It has a mild and agreeable flavor, and is not apt to turn rancid. Neither tea nor coffee possesses the nutritive oily matter of cocoa, and of the gluten which is contained so largely in tea a considerable proportion remains in the leaves when the infusion is prepared. The shells contain but little theobromine and fat, a small portion of mucilage, no starch, but much vegetable tissue or lignine. Their infusion in boiling water is much used as a substitute for tea and coffee. Its taste is somewhat like that of chocolate, but weaker.

The irregular-shaped, angular pieces into which the seeds separate by pressure after the shell is removed, are called nibs; they are the purest form in which cocoa can be purchased, being the kernel deprived of its husk and unadulterated. Their structure, exposed by the microscope, is seen to be that of minute rounded cells, which are filled with starch corpuscles and fatty matter. The fragments of the cells and the starch corpuscles may still be detected in the finely ground powder of the cocoa prepared for chocolate; and in this way the presence of undue proportions of the shells is exposed, as also of the numerous other matters used as adulterants. Cocoa should properly be the pure paste prepared by grinding the nibs between heated stones, and rolling into a flaky mass the oily product which flows out. This, when moulded and cooled, is called Hake or rock cocoa; but the name of cocoa is often applied to compositions of the pure article with other substances, which properly come under the designation of chocolate.

The oil of the cocoa is extracted for certain cosmetic unguents and applications for the hair; after which the remainder of the flour is made into an inferior article called broma, which however is much liked by many persons who object to the richness of chocolate or cocoa. - The imports of cocoa, not including chocolate, into the United States in the year ending June 30, 1872, were 4,917,809 lbs., valued at $600,640.