CHEMICAL ANALYSIS OF COFFEE. 



177 



tested, as in the tea, for the amount of sokible tannin, and steeped 

 in fifty parts of water. 



Coffee and tea as beverages in actual use were also taken and 

 analyzed and the amount of tannin estimated, with the result of 

 showing that on an average the tea contained nearly four times as 

 much tannin as the coffee. These results leave no doubt that the tea 

 we drink contains at least four or five times as much tannin as the 

 coffee we drink. Also, that the tea yields only a small proportion 

 of its large quantity of tannin at five to ten minutes' steeping. 

 And in case of poisoning by alkaloids, strong tea is better than 

 coffee as an antidote. 



As to the volatile oils. The essential oil of tea is a very small 

 but a distinct constituent of good tea. The market value of good 

 tea undoubtedly depends far more upon this volatile oil than upon 

 all other constituents. Its presence is recognized and its propor- 

 tions discerned by the expert, fi-om the odor, when hot water is 

 poured upon hot tea in a hot cup. This volatile oil is conjectured 

 to be an organic stimulant. Coffee in the green state has no vola- 

 tile oil. By the process of roasting an agreeable essential oil is 

 developed, doubtless in part from the fat present. The effect of 

 this essential oil on the human system is not at all known. It 

 may cause the digestive disturbance sometimes due to coffee- 

 drinking. 



As to the food substances, tea contains pectin, gum, legumin, 

 and other matters, yielding in all to boiling water, about thirty- 

 two per cent, of its weight. Coffee contains after roasting one or 

 two per cent, of glucose, ten to twelve per cent, of fat, nearly as 

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