210 CHEMICAL, MEDICAL AND DIETICAL PROPERTIES. 



matter. The liquor is next filtered and the filtrate evap- 

 orated down to a small bulk, first over a naked flame and 

 afterwards in a water bath, and on being allowed to cool 

 the solution will deposit crude theine which is removed 

 by filtration, and the filtration nearly dried up in the water 

 bath, and the residue boiled with alcohol, which dissolves 

 the theine out of it. From this hot alcoholic solution 

 theine crystallizes on cooling, a final purification being 

 effected by crystallization from ether and decolorizing with 

 animal charcoal. A simpler but less effective method 

 is to place the dust of finely powdered tea-leaves, or an 

 evaporated watery extract on a watch glass and cover it 

 with a paper cone and hold it over a spirit lamp or gas jet 

 the vapor arising from the glass condenses on the inte- 

 rior of the cone and forms small crystals of theine. Con- 

 centrated sulphuric acid dissolves theine in the cold 

 without the production of color, but if the alkaloid be 

 treated with nitric acid evaporated to dryness, and the 

 reddish-yellow residue moistened with a little ammonia it 

 turns a splendid purple color. Again, if a solution of 

 theine be evaporated with chlorine on a watch glass a 

 reddish-brown residue is obtained, which if again treated 

 with the vapor of ammonia it becomes a deep violet of 

 which the chief precipitants will be phosphoric acid, iodine 

 and platinum, forming a yellow and brown precipitate 

 respectively. 



Theine having no odor and only a slightly bitter 

 taste it obviously has very little to do with the 

 flavor of tea. It is, however, considered a very valuable 

 constituent on account of the large percentage of nitrogen 

 which it contains and to which is attributed the peculiar 

 physiological action of tea on the animal economy, but 

 what changes it undergoes in the human system has not 

 yet been determined. When oxydized artificially it 



