THE 



QUARTERLY JOURNAL, 



January, 1822. 



Art. I. Comparative Analysis of Black and Green Tea. 



The following experiments, made in the laboratory of the 

 Royal Institution, were chiefly undertaken with a view of as- 

 certaining whether the different effects usually attributed to 

 black and green tea, are referable to any peculiar principle exist- 

 ing in the one which is not to be found in the other. They 

 will also tend to throw some light upon the relative composition 

 of teas of different prices. To ascertain the nature and extent 

 of adulterations of any kind is not our present object: the vari- 

 ous specimens submitted to examination were obtained from most 

 respectable sources, and undoubtedly genuine as imported ; 

 what processes the tea may be submitted to in China, or what 

 mixtures and additions it may there receive, are curious and in- 

 teresting matters of inquiry, and deserve further investigation 

 than they have as yet received. 



Experiments with Black Tea, 



A 



One hundred parts of the finest black tea sold in the shops 

 at 12s. per lb., were digested in repeated portions of boiling 

 water until it entirely ceased to act upon the residue ; the leaves 

 were then dried, and were found to have lost thirty-five per 

 cent, in weight ; they retained their original colour. The in- 

 fusion was evaporated, and yielded a dark brown transparent 

 extract, very astringent, and of a nauseous bitter flavour. 



B 



The leaves, exhausted of all their matter soluble in water, 

 were digested in alcohol, (sp. gr. 820°), to which they imparted 

 Vol. Xn. P 



