142 The Fermentation of Cacao 
to the oxidation process for shorter periods 
were declared to be unripe, and sharp in 
flavour. 
The freshly-gathered and dried tobacco- 
leaves used in my experiments were kindly 
supplied to me by Herr J. Hammerschlag, 
manager of the Kaiserliche Tabak-Manu- 
faktur, Strassburg, who also submitted the 
tobacco leaves fermented by me to expert 
tests, the results of which I have given 
above. 
I have therefore proved that with tobacco 
also, fermentation plays only a_ subsidiary 
part, the object of which can be attained by 
artificial heat, but that the main results in the 
curing are attributable to the oxygen in the air. 
The essential principle of tobacco fermentation 
is then to allow the oxygen of the air to act 
on the leaves under conditions favourable to 
oxidation—that is to say, at moderately high 
temperatures. 
I have mentioned my researches on coffee 
and tobacco fermentation, in order to show 
that in their case the oxygen from the air 
also plays the same 7é/e that it does with 
indigo, tea, and cacao fermentation, or, rather, 
oxidation. In actual practice it is true that in 
the case of indigo the oxidation takes place 
in a watery solution, but if the leaves of the 
indigo plant are strongly compressed—in other 
words, if they are treated as one does when 
rolling tea-leaves—oxidation will also occur 
