The principal chemicals in tea are: caffeine, tannin and essential oil.
The chief of these are coffee or caffeine and atropine.
Caffeine (formerly known as theme) is the alkaloid of tea, and is identical with that of coffee, guarana, mate and kola nut.
It often relieves neuralgia, especially when combined with caffeine and quinine.
Inject stimulants subcutaneously; give coffee - hot and strong - by the mouth and rectum, or use large doses of caffeine citrate; and employ artificial respiration.
Dimethylparabanic acid (cholesterophane), C0[NCH 3 C0] 2, is formed by oxidizing caffeine or by methylating parabanic acid.
A pint of hot strong coffee may be introduced into the rectum, and caffeine in large doses - ten or twenty grains of the carbonate - may be given by the mouth.
Use hot bottles and stimulants, especially trying to counteract the cardiac depression by atropine, caffeine, strophanthin, &c.
The tetramethyl derivative, amalic acid, C$(CH3)4N407, has been prepared by oxidizing caffeine with chlorine water, and forms colourless crystals which are only slightly soluble in hot water.
Caffeine is the active principle in tea, coffee, kola, mate and guarana; while theobromine, a body closely allied to it, is found in cocoa and chocolate.