242 TRUE CAUSE OF COLOUR. 



the leaves in constant motion in the kuo : and of 

 the second with a moderate or slow fire in the same 

 manner ; and in both cases green tea was produced ; 

 but the colour produced by the slow fire was 

 preferable. 



2. After the second roasting and rolling of an- 

 other parcel of leaves, I divided the kuo into two 

 equal parts by means of a thin partition of wood 

 fixed in the centre ; and then placed an equal 

 quantity of leaves on either side of the wood. The 

 one I kept in constant motion, the other in as 

 quiescent a state as possible, consistently with the 

 leaves not burning, as in the inferior method 

 already described of drying black tea. The leaves 

 kept in constant motion dried rapidly, and soon 

 assumed the colour and appearance of green tea. 

 The other parcel required a much longer drying ; 

 and when completed assumed the colour of black 

 tea. 



Thus the difference of colour in black and green 

 teas does not appear to be derived from any 

 management of heat, but from manipulation ; the 

 heat being the same in both cases. I therefore 

 conclude that the colour of black teas, when 

 roasted in the manner herein described, arises from 

 the quiescent state of the leaves during the final 

 desiccation; and that of the green from incessant 

 motion — the former producing a slow, and the 

 latter a quick evaporation of the elastic fluids. 

 The fanning of the green tea seems also employed 



