CHEMICAL, MEDICAL AND DIETICAL PROPERTIES. 213 



of tannin extracted, after an infusion of thirty minutes, 

 averaged only 7.44, an almost similar result being ob- 

 tained from an examination of the finest Congou-China 

 Green teas, ranging from 11.87 to 14.11 per cent, some 

 Japan samples under the same conditions yielding on an 

 average from 8 to 10. While with a sample of the finest 

 Assam (India) a percentage of 17.73 of tannin by actual 

 weight was extracted after an infusion of only fifteen min- 

 utes, two samples of India and Ceylon giving respectively 

 18.91 and 15.26, proving conclusively that India and 

 Ceylon teas are much more heavily weighted with tannin 

 than China and Japan teas. The percentage of tannin in 

 the extract is also quite irregular, according to the quality 

 of the tea, the ratio of tannin to the extract varying quite 

 uniformly with the value of the tea, the percentage falling 

 and rising with the percentage of the extract and cost of 

 the tea. 



Volatile Oil Is the principle which imparts to tea its 

 peculiar flavor and aroma, and upon the amount contained 

 in the dried leaves depends the strength and pungency of 

 the infusion. It is present only in very small quantities, 

 but is, nevertheless, very potent in its effects, the propor- 

 tions ranging, according to Mulder, from 0.6 per cent, in 

 Black tea to 0.80 in Green, but averaging 0.75 in all good 

 teas. It is found by distilling the tea with water, is 

 lighter in body than water, citron-yellow in color, resini- 

 fying on exposure, solidifying with cold, and exerting a 

 powerfully exciting or stimulating effect on the system. 

 But there being no chemical analysis of this constituent 

 extant, its exact effect on the human system is difficult to 

 define. By some authorities it is claimed to produce 

 wakefulness, acting, it is said, in the same manner as 

 digitalis (fox-glove) which, when taken in overdoses, 

 causes anxiety and inability to sleep. It is a well-known 



