Tea, in its chemical composition, is similar to coffee, containing even a greater percentage of the alkaloid caffein, and also a larger percentage of tannic acid. Tannic acid is present in larger quantities in green tea than in the black variety. In addition to the evil effects caused by the caffein which it contains, tea is more destructive to the normal activities of the stomach because of the tannic acid. The student may get some idea of what the stomach of the tea-user has to contend with, when it is stated that tannic acid gets its name from the essential action that this substance has in the process of tanning leather.
COCOA AND CHOCOLATE
The cocoa bean, which was mentioned as the source of chocolate and cocoa-butter, is also the source of the beverage known as breakfast cocoa. The cocoa bean contains caffein, though the per cent is considerably less than in coffee or tea. Cocoa is practically free from tannic acid. For these reasons, and because of its food value, it is decidedly the least harmful of the stimulant beverages. Cocoa, though being in reality more tasteful and nutritious than either coffee or tea, is less used because it lacks the stimulating effect.
The various alkaloid poisons thus far discussed form but an infinitesimal part of the great group of articles used by old school physicians in the treatment of dis-ease, and by civilized people as stimulating and sedative beverages.
b ALCOHOLS AND RELATED COMPOUNDS
The second group of drugs which is associated with alcohol includes the ethers, chloroform, and coal-tar products. This group is also wholly of plant origin, alcohol being distilled from plant products, and coal-tar being formed from petrified plants. These drugs always contain the three elements carbon, hydrogen, and oxygen; some contain an additional element which gives them their peculiar property; for example, chloroform contains chlorin.
Coal-tar is the most wonderful source of drugs known. The distillation of this substance produces coloring matter, preservatives, poisons, and "pain killers" ad infinitum.