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The same may be said of chocolate." Playfair and Lankester: Tea contains 3 per cent. theine. Coffee " 1¾ " caffeine. Cocoa " 2 " theobromine. Probably the proportion of caffeine in coffee would be more correctly stated as 1¼ per cent. Dr. Johnson's analysis: Dried milk 35 \ Cocoa essence 34¾ \ Flesh formers in Cocoa-nibs 23 / each hundred parts. Best French chocolates 11 / Mr.
Caffeine and theobromine have also quite different relations. Caffeine, it will be remembered, is the methyl ester of theobromine, and can be prepared from it. When caffeine is carefully oxidized with chlorine, it yields dimethyl-alloxan and methyl-urea. Both theobromine and caffeine are decomposed by heating to 240° C. in sealed tubes with hydrochloric acid, identical products being obtained.
It is hardly necessary the principles should have different names, as they have been found by chemists to be identical; the essential spirit of cocoa and chocolate, theobromine, though not identical, having many of the same properties. Tea is valuable chiefly for its warming and comforting qualities.
These products are carbon dioxide, formic acid, ammonia, methyl-amine, and sarcosine, the last three being of course in combination with the excess of hydrochloric acid. The artificial preparation of theobromine and caffeine from xanthine, and guanine also show clearly their relations.
In a hundred parts of chocolate are found forty-eight of fatty matter or cocoa-butter, twenty-one of nitrogenous matter, four of theobromine, eleven of starch, three of cellulose, three of mineral matter, and ten of water; there being also traces of coloring matter, aromatic essence, and sugar.
Guayaquil, in the republic of Ecuador, on the west coast of South America, produces the largest output in the world. This cacao has a bold bean and a fine flavour, and is rich in theobromine; it is much valued on the market, and its strength and character render it indispensable to the manufacturer.
Piperine has also been made by the uniting of piperidine and piperic acid, and, as piperidine has already been formed from pyridine, we have here a true synthesis also. Both theobromine and caffeine, its methyl derivative, have been made from xanthine, which itself can be formed from guanine, a constituent of guano.
Caffeine and theobromine, the narcotic principles of coffee and tea, are xanthines; and so is the nicotine contained in tobacco. Peas, beans, lentils, mushrooms and peanuts, besides being very rich in uric acid-producing proteins, carry also large percentages of xanthines, which are chemically almost identical with uric acid and have a similar effect upon the organism and its functions.
The active principle of tea is called theine; that of coffee, caffeine, and of cocoa, theobromine. They also contain an aromatic, volatile oil, to which they owe their distinctive flavor. Tea and coffee also contain an astringent called tannin, which gives the peculiar bitter taste to the infusions when steeped too long. In cocoa, the fat known as cocoa butter amounts to fifty per cent. Tea.
The theine in tea and the theobromine in cocoa are so similar to caffeine that chemists can not differentiate them. These drinks when first taken cause a gentle stimulation under which more work can be done than ordinarily, but this is followed by a reaction, and then the powers of body and mind wane so much that the average output of work is less than when the body is not stimulated.
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