8 5 + 



THE POPULAR SCIENCE MONTHLY, 



part of it is extracted in the beverage as 

 usually prepared, both of tea and coffee. A 

 pound of tea usually furnishes from three 

 to five times as many pints of beverage as 

 are obtained from a pound of coffee, but 

 the ways of preparing and the estimates are 

 so different that nothing exact can be de- 

 termined on this point. As a whole, the 

 proportions for given volumes of beverage 

 can not be declared habitually much larger 

 in the one than in the other ; if there is any 

 difference, the coffee-beverage is likely to 

 be the stronger. The tannins are tannic 

 acid in both substances bohcic and gallic 

 acid in tea, and caffeic acid in coffee, all 

 astringents. Tea contains, according to the 

 analyses relied upon by Dr. Prescott, from 

 six to twenty per cent., an average of twelve 

 per cent, of tannins ; some other estimates 

 make the percentage very much larger. This 

 large amount is, however, by no means all 

 dissolved in the ordinary preparation of tea 

 as a beverage. No tannin was dissolved in 

 steeping for five minutes six out of eleven 

 specimens of different qualities of tea at the 

 Michigan University, and the percentage of 

 the other five specimens was not large, the 

 average percentage of the whole being only 

 008. After thirty minutes' steeping, the 

 quantity of tannin dissolved varied from 

 l - 09 to 4'50 per cent., the average being 

 2-49, and was in no case equal to half the 

 amount contained in the tea. A larger 

 quantity of tannin was extracted in other 

 experiments in which the tea had been mac- 

 erated at ordinary temperature before boil- 

 ing. The tannin in coffee-berry, by all re- 

 ports, is not more than one third the quan- 

 tity of that in tea-leaves, and may be con- 

 siderably less. Six specimens of coffee were 

 steeped for five minutes without yielding 

 any tannin ; two of them showed a trace 

 of tannin after ten minutes' steeping ; after 

 twenty minutes', five of the specimens 

 showed from - 01 to 0'25 ; after thirty min- 

 utes', the proportion of tannin given up va- 

 ried from - 09 to 1"80, the average being 

 - 83. Other analyses show that tea contains 

 an average of - 206 grains, coffee 0'055 

 grains, of tannin to the fluid ounce of the 

 beverage in use. 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, and that the tea yields 



only a small proportion of its large quantity 

 of tannin, after from five to ten minutes of 

 steeping. If tea or coffee is to be admin- 

 istered, as in any case of poisoning by alka- 

 loids, tea, well steeped, is to be chosen as 

 the better antidote for the precipitation of 

 alkaloids, and equally potent as a stimulant. 

 The essential oil of tea is a very small but 

 distinct constituent, the most important fac- 

 tor in determining its market value. It is 

 conjectured to be an organic stimulant, and 

 may promote perspiration. Coffee, in the 

 unroasted berry, has no volatile oil ; but, in 

 roasting, an agreeable essential oil is devel- 

 oped, the effects of which are not known, 

 but which may cause the digestive disturb- 

 ance sometimes ascribed to coffee-drink- 

 ing. Of nutrient substanc.es, tea contains 

 pectin, gum, legumine, and indeterminate 

 matters, yielding, in all, to boiling water 

 about thirty-two per cent, of its weight. 

 Coffee contains, after roasting, from one to 

 two per cent, of glucose, ten to twelve per 

 cent, of fat, nearly as much legumine, and a 

 little gum, and yields thirty-five per cent, to 

 water. " It is not unlikely," Dr. Prescott 

 concludes, " that these food-substances, as 

 modified by roasting, disagree with the di- 

 gestion of many persons. This is, let me 

 submit, a not improbable explanation of the 

 class of injurious effects of coffee-drinking, 

 when the substitution of tea-drinking gives 

 relief. The powerful nerve-stimulant, caf- 

 feine, as we have seen, is obtained in about 

 as large doses from tea as from coffee. The 

 caffeine of both these beverages undoubt- 

 edly produces injury to the nervous system 

 in many cases ; but, when coffee causes 

 palpitation, sleeplessness, etc., not resulting 

 from tea, let me suggest that some atten- 

 tion be paid to the digestive organs." 



Water in Disease. Dr. S. G. Webber, m 

 the " Archives of Medicine " for August, at- 

 tributes a considerable value to water as a 

 preventive and a remedy of disease, and op- 

 poses the abstinence from drinking at meals, 

 advocated by many, as injurious. Among 

 patients who have come under Dr. Web- 

 ber's care affected with "symptoms of an 

 undefined character, a vague unrest and dis- 

 quiet showing itself by discomfort or even 

 pain, sometimes in one place, sometimes in 

 another," with constipation and an unhealthy 



