TEAS ADULTERATED WITH FOREIGN LEAVES. 883 
reliance can be placed on the results of such calculations, owing to the 
sourees of error already named. If a tea contains less extract matter 
than the minima given by Geisler, the kind of tea being taken into 
-gecount, it may be placed on the doubtful list, and if all other conditions 
agree it may be considered to have been adulterated by the addition of 
spent leaves. In investigating this form of adulteration the appear- 
ance of the leaf must largely determine the chemist’s decision. If the 
leaves are very much broken, frayed, or partly unrolled, there is evi- 
dence of spent tea. For the examination, the suspected sample is 
soaked in water and the softened leaves are unrolled and examined on 
a glass plate. The following averages of the soluble constituents of 
genuine teas are given for comparative purposes. The analyses of 
Geisler are given above, so far as they relate to the extract. 
Table showing the maxima, minima, and mean percentages of the principal soluble con- 
stituents of tea. 
} 
Indian Line is Black Oolong | Congou Green ee aS 
teas, ae teas, teas, teas, teas, PY gee: 
A ag lon Leas, res Jan Janta , ea Jesse P.| Jesse P. 
David - Hassall. | Batter- | Batter- 
Geisler. | Hassall. Geisler. Geisler. 
Hooper. | shall. shall. 
Maxima... 18. 86 21. 22 on) 5 8 20. 07 oY. gt An eee RS EU92 Li | Meee 
Tannin.< Minima. .-- 13. O4 10.14 Etc eh Set 11. 93 che Sl pee Ae eee SENSE SSS eS 
lane sam. 14. 87 WGP os Le 16. 38 i ee Os os Ae eee ee 
sae = gg eet ae 3. 04 3. 50 2, 87 Thee le ee 
Theine.{ Minima... <p eee 1.36 1.15 1.70 RS eee s |S ee Le eee 
| Mean. es 3 es eee 2. 08 2.32 2. 37 | DAG hes shyt he lonice cee 
ipseer = TAC eee ae 5 Se ee BAT 1 Ps Sea ee cat A 5 PE ps eek ess Se 
Soluble "Minima. .. ye eee tenets 2. 60 See oF Et ety I es 
{team tie Tred Py eon ee Sere 3. 20 OG iyi ite oe 3.44 3. 60 
Tie ditterences between the highest and lowest percentages of each 
constituent are so marked that little possibility of detecting other than 
exceedingly gross adulteration, by the admixture of spent leaves, is 
afforded by these analytical data. 
- The total ash of genuine teas, according to various authorities, ranges 
from a little below 5 to nearly 7 per cent, the iron from .08 to .17 per 
cent, and the silica from .14 to .80. 
FOREIGN LEAVES. 
The addition of foreign leaves 1s best detected by means of the micro- 
scope. The leaf of the tea plant is quite characteristic in its venation, 
serration, aud stomata. The veins recurve before reaching the border 
of the leaf and each forms a loop with its neighbor. The serrations are 
almost lacking in very delicate leaf buds, but are very distinct in the 
older leaves. Plates xxxiv and XL have been prepared to illustrate 
the leaf of the tea plant and other leayes which are said to have been 
20393—No, 13——2 
