No substances are so essentially necessary to mankind, or form such important articles of commerce, as those which we come first to consider, the dietetic products--cacao, coffee, tea, and sugar. The consumption of these in all civilized countries is immense, notwithstanding that in many they have been fettered with heavy fiscal duties. The investigation of the culture of the plants from which they are obtained, and the manufacture of the products, is a very curious object of research. CACAO OR COCOA. The chocolate nuts or seeds, termed cacao, are the fruit of species of _Theobroma_, an evergreen tree, native of the Western Continent. That commonly grown is _T. cacao_; but Lindley enumerates two other species, _T. bicolor_, a native of New Granada; and _T. Guianensis_, with yellow flowers, a native of Guiana. The seeds being nourishing and agreeable to most people, are kept in the majority of houses in America, as a part of the provisions of the family. By pressure they yield fatty oil, called butter of cacao. They also contain a crystalline principle analogous to caffeine, called theobromine. The common cacao of the shops consists generally of the roasted beans, and sometimes of the roasted integuments of the beans, ground to powder. The consumption of cacao in the United Kingdom is about three millions of pounds annually, yielding a revenue of £15,500. Few tropical products are more valuable or more useful as food to man than cacao. It is without any exception the cheapest food that we can conceive, and were it more generally employed, so that the berries should not be more than two, three, or, at most, six months old, from the time of gathering (for, if kept longer, they lose their nutritive properties), even a smaller quantity than that usually taken in a cup would suffice: in fact, cacao cannot be _too_ new. The cacao beans lie in a fruit somewhat like a cucumber, about five inches long and three-and-a-half inches thick, which contains from twenty to thirty beans, arranged in five regular rows with partitions between, and which are surrounded with a rose-colored spongy substance, like that of water melons. There are fruits, however, so large as to contain from forty to fifty beans. Those grown in the West India islands, as well as Berbice and Demerara, are much smaller, and have only from six to fifteen; their development being less perfect than other parts of South America. After the maturation of the fruit, when their green colour has changed to a dark yellow, they are plucked, opened, their beans cleared of the marrowy substance, and spread out to dry in the air. In the West Indies they are immediately packed up for the market when they are dried; but in Caraccas they are subjected to a species of slight fermentation, by putting them into tubs or chests, covering them with boards or stones, and turning them over every morning to equalize the operation. They emit a good deal of moisture, and lose