METHODS OF DETERMINING ADULTERANTS. S89 
Analyses of first-crop China teas of the season of 1890—Continued. 
Total | 
amount of | Products 
Num- Products Extract- theine,tan-| Theine, Tannin, of fermen- 
berof Water. Theine. Tannin. offermen- ive sub- nin, and | percent percent] tation, 
tea. tation. stances. products of Oi AG% | per cent 
fermenta- | ae 
tion.* 
Uh hae a ee 2.87 10. 05 1.74 33. 90 14. 66 19. 92 68.50 11. 68 
ig eo ee eee 2.83 10. 07 1.35 33.15 14. 25 19. 87 70. 66 . 9.47 
14 8.07 2.88 9. 65 1.65 30. 92 14.17 , 20. 33 68.10 | 1-57 
| a ae 2. 82 9.36 1. 59 33. 00 7 20. 55 67. 90 1 oo 
i A See ee 3. 11 10. 03 1.70 32. 21 14. 84 20. 96 67.59 11. 45 
17 8.10 3. 00 9. 36 1.838 34. 12 14. 24 20. 02 65. 73 13. 25 
lo Se eee 3.10 10. v0 1.50 34. 10 1+. 60 21. 23 68. 50 10. 27 
cL ee a 3.16 9. 80 ards 33. 66 14. 71 21.48 66. 62 11. 90 
=) Sa 3.02 9.37 1.50 32. 40 3. 89 21. 74 67. 46 10. 80 
21 9.08 3. 00 9.45 1.18 * 33. 80 13. 63 >. 02 69.33 8.65 
22 7. 84 3. 00 8. 84 1.18 32. 20 3. 02 %, 05 7.89 9. 06 
23 | 8. 85 3.02 9.05 90 33.00 12.97| 23.29 69.77 | 6.94 
24 | 8. 20 3. 27 9.21 | 1.44 34.95 15. 92 23.50 66.16 | 10. 34 
23 | 8.24 3. 25 9.14 1.25 32. 93 13. 64 . 23. 84 67.00 | 9.16 
%| 9.13 3.41 9.32 144 -33.26 1417| %07| 6.77) 10.16 
27 | 9.78 3.33 9. 22 127 32. 00 3. 82 24.1) 66. 71 9.18 
28 | 8. 42 3.45 9.42 1. 38 34.80 | 14.25 | 2A. 22 66. 10 9. 68 
7.83 3.21 ‘9. 00 1 | 
Ba IZ 33. 46 13. 38 24. 52 67. 26 8. 22 
* Total amount of theine, tannin, and products of fermentation is represented by A for brevity. 
ANALYTICAL METHODS. 
In the following paragraphs are presented the methods adopted for 
the estimation of the various constituents of teas. 
Caffeine or theine, CsH).NsO2.—After experiments with a number of methods for 
the estimation of caffeine, the following was adopted on account of its simplicity and . 
the accuracy of the results: 
1Transfer 3 gs of powered tea into a 300 ce flask, add abont 250 ce of water; heat 
gradually to the boiling point, using a small fragment of tallow to prevent frothing; 
boil gently 30 minutes, washing down any particles of tea which may collect on the 
flask above the liquid. After the liquid begins to boil the flask should be filled al- 
most to the neck and water should be occasionally added to keep its level at this 
point. Several samples may easily be extracted in this way at the same time, since 
they require but little attention after regulating the flame of the lamp. After boil- 
ing 30 minutes, cool, add a strong solution of basic acetate of lead in sufficient quan- 
tity for the removal of precipitable substances; usually about 3 cc are required ; com- 
plete the volume to 300 cc, mix thoroughly, and filter, rejecting the precipitate un- 
washed. Treat 50 cc of the filtrate with H.S for the removal of the lead; boil off the 
excess of H,S; filter into a separatory funnel, washing the precipitate with hot water, 
or an aliquot part of the filtrate may be taken and washing of the precipitate may 
thus be avoided. The error from the volume of the precipitate is very slight. 
Extract the water solution in the separatory funnel seven times with chloroform ; 
collect the chloroform solution of caffeine in a small] tared flask, and remove the 
solvent by distillation; dry the caffeine at 75° C. two hours, weigh, and calculate 
the percentage. 
1 Jour. anal. Chem. 4, 4, p. 390, 
