CHEMICAL CONSTITUENTS. 255 



acting and reacting upon each other, these three con- 

 stituents give to coffee its peculiar properties and effects 

 on the human system. 



To the chemist, coffee and tea are much the same, 

 their two alkaloids, caffeine and theine, being to them 

 undistinguishable one from the other, each also con- 

 taining a volatile or essential oil, the difference in the 

 taste of which is doubtless due -to subtle properties 

 which the chemist is so far unable to detect. For this 

 reason the following comparative analysis of coffee and 

 tea may be found interesting, as showing how closely 

 they are chemically allied : 



Constituents. Coffee. Tea. 



Water, 12.0 5.0 



Theine, 0.75 0.5 



Tannin, 5. 15.0 



Gluten, 13.0 25.0 



Wood fibre, 34.0 24.0 



Volatile oil, 13.0 4.0 



Gum and sugar, 15.0 21.0 



Ash or residue, 7.0 5.0 



From recent experiments it appears that the quantity 

 of tannin in the coffee bean is not over about one-third 

 of that contained in the tea leaf and frequently is consider- 

 ably less, six samples of coffee being tested in the same 

 manner as tea for the amount of soluble tannin, and 

 steeped in fifty parts of water. Equal quantities of coffee 

 and tea were also analyzed and the amount of tannin 

 estimated with the result that, on an average, tea yielded 

 nearly four times as much tannin than the coffee, which 

 proves that in case of poisoning by alkaloids strong tea 

 is better than coffee as an antidote. When used in 

 equal quantities tea yields about twice the amount of 

 theine that coffee does to the water in which it is 



