Caffeine, also called trimethylxanthine (C8H10N4O2),
a white, bitter alkaloid extracted from
coffee, and also found in tea, cocoa, cola, and ilex (holly) plants. Caffeine
stimulates the central nervous
system and heart, and is a diuretic.
It increases alertness, in excess causing insomnia,
and is mildly addictive. It is often included with aspirin or codeine in analgesic preparations. Melting point 238°C.