Vlll PREFACE. 



question frequently discussed at the tea-table, 

 namely, " In what consists the difference between 

 black and green tea ? " To the wholesale and retail 

 dealer, if the task has been fairly executed, each 

 page ought to have its interest ; and the merchant 

 will find, on reference to the heads of chapters, 

 more than is promised by the title-page, on subjects 

 regarding price, and other topics of trade. For 

 the chemist some experiments are detailed, and a 

 novel theory is submitted for further development 

 from his science, as to a change in the constituents 

 of black tea, which is traced to a process of mani- 

 pulation previous to roasting, on which its darkness 

 and redness of colour in leaf and infusion, as well 

 as flavour, is supposed to depend. In the de- 

 velopment, however, of this theory, I must claim 

 the indulgence of the man of science, a character 

 to which I make no claim. 



The highly responsible and laborious official 

 duties of my appointment under the East India 

 Company, left me little leisure for literary pursuits 

 during the season of activity at Canton ; and 

 during the recess at Macao, it must be acknow- 

 ledged that I found the enervating effects of a 

 hot climate on a northern constitution indispose 

 both body and mind to much exertion. It must also 

 be confessed that the extreme retirement of my 

 former life in China, with the absence of com- 

 munion with literary and scientific men, as well as 

 an imperfect supply of books, were great drawbacks 



