OF VARIOUS KINDS OF TEA. 
21 
entirely removed, while by over-fermentation much of the fine 
flavour is lost and even a sour taste is conferred upon the tea. 
The best token for judging the course of fermentation is the 
colour of the interior of the ball or layer. In general, fermenta¬ 
tion is interrupted when half the twisted leaves inside the ball 
shall be rusty red and half of them green. The external surface 
of the ball does not give any sure sign of the advancement 
of the fermentation, its colour being varied according to the 
extent to which the leaves were withered ; viz, dark greenish 
red with over-withered leaves, and greenish yellow with under¬ 
withered leaves. The duration of fermentation is, of course, 
governed by the temperature of the air as well as the nature 
of the leaves, the higher the temperature, or the more succulent 
the leaves, the quicker the fermentation, and vice versa, being 
generally 40-60 minutes. The best temperature is generally 
said to be 40°C, since, though at higher temperatures, fermen¬ 
tation goes on more quickly, there is a risk of going too far 
with a little negligence. 
I must not pass over in silence a preliminary trial on the fer¬ 
mentation of the leaves, consisting simply of the observation 
of the temperatures of the ball and of the air. The following 
are the results. 
Temperature, °C. 
_Increase. 
Duration. of the interior of the ball, of the air. °C. 
At the commencement 
29.5 
27.O 
+ 
2.5 
after 15 
minutes. 
3°-5 
26.5 
»» 
4.0 
,, 20 
1) 
31-5 
25*5 
»» 
6.0 
.. 7° 
*» 
33-25 
2 4-75 
8.5 
» no 
»» 
34-5 
24.0 
10.5 
.. 15° 
33-° 
22.0 
»» 
n.0 
„ 190 
♦ ! 
32.0 
22.0 
>> 
10.0 
,, 230 
n 
3 I -5 
22.0 
»» 
9-5 
■. 270 
»» 
30.0 
22.0 
»> 
8.0 
» 310 
11 
29.5 
22.0 
»1 
7.5 
After g hours from 
the last observation 
23.5 
21.0 
+ 
2-5 
