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Chocolate is made from the powdered cocoa mixed with sugar and other materials. Chocolate, like tea and coffee, depends for its effect on an extremely powerful drug, _theine_ or _caffeine_, of which it contains minute proportions. There are very few other plants known which possess this powerful substance. Amongst these is the Kola nut, which is everywhere regularly employed in West Africa. On the way up to the barracks at Freetown, Sierra Leone, natives were always to be seen seated by the roadside; they sold kola nuts to the soldiers, who were thereby enabled to walk steadily and uprightly past the sentry, and to return his challenge in a clearly articulate voice, although they might previously have been somewhat injudiciously convivial in the town. This kola is one of the very strongest nerve tonics; under its influence men can endure severe physical and mental strain. Like the others, however, a depressing reaction inevitably follows, accompanied by insomnia, headache, and other evil effects.