The seeds of at least two plants are used as important adjuncts to our list of foods, and can be enumerated among foods without any impropriety. These are coffee and cocoa. They contain nutritive properties,--the latter in very much higher degree than the former,--and they possess also peculiar constituents which entitle them to rank as luxuries. These peculiar constituents are (1) flavoring matters, and (2) an active principle. But, either from its constitution or from its association in the seed, the active principle of coffee, although it has nearly or quite the same ultimate composition as the active principle of cocoa, is unlike it in its effects. The active principle of cocoa is substantially free, as used in its preparations, from any undesirable effects on the nervous system. This active principle of cocoa is _Theobromine_. The essentials of a perfect food are (1) a certain amount of carbohydrates, (2) of albuminoids, and (3) certain mineral matters, these latter being substantially the same in all seeds used as food. In cocoa these three groups are combined in proper proportion to constitute a complete food, but there is superadded the active principle, _Theobromine_, which places it at once in the class of luxuries as well as of necessary foods. When cocoa-seeds are prepared properly for food, without doing violence to the chemical relations of the different components, a comforting nutritive article of the highest value is obtained. This ideal method of preparation is not a chemical torturing by the addition of foreign ingredients, as in the alkali process, but it consists in the complete unlocking, by perfectly natural, mechanical means, of all the virtues of the seeds. We do not try to render the albuminoids of wheat and other grains soluble by means of ammonia, soda, or potash, nor do we think it desirable to increase the solubility of the albuminoids of egg and meat by adding caustic or carbonated alkalies to them before they are used. And yet chemical processes analogous to these have been devised and are sometimes used with regard to cocoa. In most cases these added substances are detected in the increased amount of mineral matters found in the ash after burning the preparation. The amount of ash in pure cocoa is about four per cent. Any appreciable amount above this may be attributed to the admixture of mineral matters used in the preparation. The oil in pure chocolate-seeds is about fifty per cent of the whole weight. Although the oil is exceedingly bland and free from rancidity, it has been found expedient in some cases to withdraw a part of this oil, leaving a smaller amount in the product. This is the method pursued in the manufacture of the powdered cocoas. With this reduction in the quantity of oil, the resultant beverage is less likely to disagree with delicate digestion.