FOREGOING PROCESS. 153 



saccharine matter was altogether destroyed, and 

 with it those elements on which excellence of qua- 

 lity depends. The dried leaves also became pallid 

 and yellow, the infusion as light-coloured as green 

 tea, and almost flavourless. This experiment fur- 

 ther proves, what has already been explained, that 

 no measure of time or degree of heat can be given 

 for the roasting and drying of tea : they both depend 

 on the state of the leaves, as regarding their succu- 

 lency and aqueous condition, the mode of manipu- 

 lation, and the kind of tea required to be made. 



9. This example, moreover, shows that what was 

 here effected by excess of temperature, as con- 

 nected with the state of humidity of the leaves, 

 though at a low degree of heat, was not very dis- 

 similar to that which takes place in nature under 

 the ordinary conditions of decay. Thus in autumn 

 the leaves of deciduous trees having performed the 

 several functions for which they were destined in 

 the production of flowers, fruit, and wood, are no 

 longer required : assimilation is impeded, they 

 begin to absorb oxygen from the air, decay and 

 dryness follow, the leaves change colour and fall, 

 and nothing remains but red, or brown, or yellow 

 cellular tissue, and woody fibre. We will here 

 leave these experiments for the present, though we 

 shall have occasion to recur to them, when we come 

 to treat specifically of the degree of heat employed 

 in the manipulation of tea, and of its chemical 

 constituents after desiccation. 



