Dr. Stenhouse on Theine and its Preparation. 433 



The salt employed for the first two determinations was 

 washed with alcohol, and that for the last two with aether. 

 This double salt appears therefore much more stable than 

 the hydrochlorale of theine. I am proceeding to determine 

 the quantity of its other constituents. 



Complete Analysis of the Theine prepared by Sublimation*. 



0'285 gr. of the substance gave 0-5125 carbonic acid and 

 0-132 water. When burnt with oxide of copper, eight tubes 

 gave carbonic acid and nitrogen in the proportion of four to 

 one. 



Theine from Paraguay Tea. 



Through the kindness of my friend Professor Gardner, I 

 have procured an additional quantity of Paraguay tea, which 

 has enabled me to complete the analysis of the theine it con- 

 tains, and also to determine its quantity. The easiest and 

 most ceconomical way of obtaining theine from Paraguay tea 

 is by sublimation. The filtered infusion of the tea, after being 

 treated with acetate of lead and the precipitate removed, 

 should be boiled with an excess of litharge, the clear liquid 

 evaporated to dryness and sublimed with the usual precau* 

 tions. One quantity of two pounds yielded 1 2*5 grs. of anhy- 

 drous theine, and a second quantity of equal amount, which 

 was more successfully treated, gave 14-5 grs. = 0-13 per cent. 

 This is about half the quantity which most kinds of coffee 

 yield, which I have found to vary from 12 to 18 grs. for a 

 pound, and about ten times less than Chinese tea, a pound of 

 which yields from 70 to 90 grs. 



* The portion of this paper read May 2, begins here. 

 Phil. Mag. S. 3. Vol. 23. No. 154. Dec. 1843. 2 F 



