Note: Do not rely on this information. It is very old.
CaffeineCaffeine, or Theine, the active constituent of tea and coffee, in which it occurs to the extent of about 3 and 1.3 per cent. respectively. It was discovered in coffee by Runge in 1820, and in tea by Oudry in 1827. It is closely allied to theobromine, the corresponding constituent of cocoa. It forms silky needle-like crystals, slightly soluble in water and alcohol. In large doses it acts as a poison.