Of the many varieties, Mocha and Java are finest in flavor, and a mixture of one-third Mocha with two-thirds Java gives the drink at its best.

As in tea, there are three chief constituents: (1) A volatile oil, giving the aroma it possesses, but less in amount than that in tea.

(2) Astringent matter,--a modification of tannin, but also less than in tea.

(3) Caffeine, now found identical with theine, but varying in amount in different varieties of coffee,--being in some three or four per cent, in others less.
The most valuable property of coffee is its power of relieving the sensation of hunger and fatigue.

To the soldier on active service, nothing can take its place; and in our own army it became the custom often, not only to drink the infusion, but, if on a hard march, to eat the grounds also.