A constituent called Theine has also been discovered in tea, supposed to be identical with Caffeine, one of the constituents of coffee.

So while the thyroid raises the energy level of the brain, and the whole nervous system, as a byproduct of its general awakening effect upon all the cells of the body, the pituitary probably stimulates the brain cells more directly, perhaps in the manner of caffeine or cocaine.

The active principle of tea is called theine; that of coffee, caffeine, and of cocoa, theobromine.

They strongly resemble coffee in appearance and flavour, are very refreshing and appetising, but are free from caffeine, and quite innocuous.

Why not feed our souls on maxims, like those who spread the board for courses of a bovril lozenge apiece, two grains of phosphorus, three of nitrogen, one of saccharine, a dewdrop of alcohol, and half a scruple of caffeine to conclude?

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.

The artificial preparation of theobromine and caffeine from xanthine, and guanine also show clearly their relations.

Both theobromine and caffeine, its methyl derivative, have been made from xanthine, which itself can be formed from guanine, a constituent of guano.

Yet cocaine is chemically very different from caffeine, simply producing a similar physiological effect in much smaller doses.

In this way the proposition is to first measure coca against tea, then coffee against guarana, and finally to compare the four agents, using pure caffeine as a kind of standard to measure by.

The first trial to combat or prevent this drowsiness was made with caffeine.

The 3 grain dose of caffeine repeatedly obviated all this discomfort up to ten o'clock, but did not prevent the habitual, prompt, and sound sleep, from the time of going to bed till morning.

This gave no very definite effect, but 2½ drachms did give a definite effect, and a subsequent dose of 2½ fluid drachms of a well made fluid extract of coca gave about the same effect as 2½ grains of caffeine.

Three fluid drachms of the fluid extract were about equivalent to 3 grains of caffeine.