282 



TEA DISTRICTS OF CHINA. 



Chap. XVI. 



The plants are brought to us by the growers or col- 

 lectors from the country, tied up in bundles, and 

 when they arrive fresh and cool they dry of a good 

 bright green colour ; but on the contrary, it is found 

 that if they are delayed in their transit, or remain in 

 a confined state for too long a period, they become 

 heated, from a species of spontaneous fermentation, 

 and when loosened and spread open emit vapours, 

 and are sensibly warm to the hand : when such 

 plants are dried, the whole of the green colour is 

 found to have been destroyed, and a red-brown and 

 sometimes a blackish-brown result is obtained. I had 

 also noticed that a clear infusion of such leaves eva- 

 porated carefully to dryness was not all undissolved 

 by water, but left a quantity of brown oxidised ex- 

 tractive matter, to which the denomination Apothem 

 has been applied by some chemists ; a similar result 

 is obtained by the evaporation of an infusion of black 

 tea. The same action takes place by the exposure 

 of the infusions of many vegetable substances to the 

 oxidising influence of the atmosphere ; they become 

 darkened on the surface, and this gradually spreads 

 through the solution, and on evaporation the same 

 oxidised extractive matter will remain insoluble in 

 water. Again, I had found that the green teas, when 

 wetted and re-dried, with exposure to the air, were 

 nearly as dark in colour as the ordinary black teas. 

 From these observations, therefore, I was induced to 

 believe that the peculiar characters and chemical dif- 

 ferences which distinguish black tea from green were 

 to be attributed to a species of heating or fermenta- 



