272 COLOUR NOT DUE TO HIGH TEMPERATURE. 



(chap. 9. p. 242. § 2). It may, however, be said that 

 the black tea leaves took a longer time to dry ; 

 and therefore received a greater amount of heat, 

 which is equal to higher temperature. But if the 

 capacity of the leaves for heat is dependent on 

 their aqueous condition, then the use of a high 

 or low temperature causes no other effect than to 

 produce, as in water, a quick or slow conversion of 

 the fluids into a gaseous state : no more heat is 

 received by the leaves in either case. The one is 

 a rapid process of drying by quick evaporation ; 

 the other a slow one by slow evaporation. It is 

 a question of time, not of heat. It is true that 

 slow evaporation causes a greater expenditure of 

 heat and fuel, but that is due to loss of heat, in 

 consequence of slow absorption. 



Again, if equal states of dryness in tea require 

 equal amounts of heat, as some scientific and 

 practical men seem to believe, then there are no 

 solid grounds for supposing that green tea is less 

 perfectly dried than black. Indeed I have always 

 inclined to the opinion that the contrary is the 

 fact. As, however, Mulder considers black tea 

 more friable than green tea, and ascribes the quality 

 to high drying and high temperature, I was 

 induced to request the favour of Mr. Warington, 

 the chemical operator at Apothecaries' Hall, to put 

 this question to the test of experiment. After 

 experiment, it was his belief, though contrary to 

 his previous opinion, that both teas, black and 



