CHEMICAL, MEDICAL AND DIETICAL PROPERTIES. 209 



whether this large percentage of nitrogen was wholly 

 due to the theine or in part to some other principle, he 

 next found that the precipitate with sub-acetate of lead 

 contained no apparent quantity, and then testing the 

 theine by a modification of Mulder's process obtained 

 from Green tea an average of 248 per cent., and from a 

 mixture of Green and Black 2.70. But greatly as these 

 quantities exceed those of all other chemists, they were 

 still unable to account for the whole amount of nitrogen 

 found in the infusion, so by adding mere acetate of lead 

 and ammonia, separating them by filtration, and passing 

 through it a current of sulphuretted hydrogen to pre- 

 cipitate the lead, and evaporating the liquid with a gentle 

 heat he obtained an abundant supply of crystals of theine. 

 This supply he still further increased by re-evaporation 

 until the whole amounted to 3.48 per cent, of the entire. 

 There still remaining a syrup containing some theine it 

 was precipitated with tannic acid, the result being added 

 to that already crystallized it yielded a total of 5.84 from 

 Green tea in the natural state and 6.21 in the dried 

 leaf. These experiments being further continued by 

 boiling the exhausted leaves with potash, it showed a 

 presence of caseine to the extent of 28 per cent, of the 

 mass, the proportion of the latter substance in the raw 

 leaf being only 14 to 15. 



Theine is extracted from tea by boiling a quantity of 

 the leaves in a considerably larger quantity of distilled 

 water and the liquor squeezed out of the leaves which are 

 to be boiled with a fresh quantity of water and again 

 subjected to pressure, the process being repeated a third 

 time. The several portions of the infusion expressed 

 from the leaves are put in the same vessel, mixed together 

 thoroughly and treated with an excess of acetate of lead 

 and ammonia, which precipitates the tannin and coloring 



