Teas of Commerce. 243 



The question presents itself then — from whence do those 

 distinguishing peculiarities arise, and to what are they to be 

 attributed ? From observations made in other directions, in 

 the course of the routine work of the establishment to which 

 I am attached, I had formed in my own mind certain con- 

 clusions on this subject — I allude to the exsiccation of medi- 

 cinal herbs ; these are for the most part nitrogenous plants, 

 as the Atropa belladonna, the Hyoscyamus niger, the Conium 

 maculatum, and others. The plants are brought to us by the 

 growers or collectors 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 delafyed 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 brorvn and sometimes 

 a blackish-brown result is obtained. I had also noticed that a 

 clear infusion of such leaves evaporated carefully to^dryness 

 was not all undissolved by water, but left a quantity of brown 

 oxidized extractive matter^ to which the denomination Apothene 

 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 vege- 

 table substances to the oxidizing influence of the atmosphere ; 

 they become darkened on the surface, and this gradually 

 spreads through the solution, and on evaporation the same 

 oxidized 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 charac- 

 ters and chemical differences which distinguish black tea 

 from green, were to be attributed to a species of heating or 

 fermentation, accompanied with oxidation by exposure to the 

 air, and not to its being submitted to a higher temperature 

 in the process of drying, as had been generally concluded. 

 My opinion was partly confirmed by ascertaining from parties 

 conversant with the Chinese manufacture, that the leaves 



