7(? FOOD AND DRINK. 



body; it tranquilizes, but does not disqualify for labor; 

 and hence it is highly esteemed by persons of literary pur- 

 suits. 



36. Another property of coffee is, that it diminishes the 

 waste of the tissues, and consequently permits the per- 

 formance of excessive labor upon an economical and in- 

 adequate diet. This has been tested among the miners of 

 Belgium. Their allowance of solid food was below that 

 found necessary in prisons and elsewhere; but, with the 

 addition of about four pints of coffee daily, they were en- 

 abled to undergo severe labor without reducing their mus- 

 cular strength. The caravans which traverse the deserts 

 are supported by coffee during long journeys and length- 

 ened privation of food. Among armies it is indispensable 

 in supplementing their imperfect rations, and in relieving 

 the sense of fatigue after great exposure and long marches. 

 When taken with meals, coffee is also thought to promote 

 digestion. 



37. Tea. The effects of tea-drinking are very similar 

 to those of coffee, and are due to a peculiar principle called 

 thein. This principle is probably the same as that found 

 in coffee, caffein, since the chemical composition of both 

 is precisely alike. Tea, as a beverage, is made from the 

 dried leaves of the plant by the addition of hot water; if 

 the tea is boiled, the oil which gives it its agreeable flavor 

 is driven off with the steam. There are two kinds of 

 tea the black and the green : the latter is sometimes in- 

 jurious, producing wakefulness and other nervous symp- 

 toms. The excessive use of either coffee or tea will cause 

 wakefulness. 



38. During Dr. Kane's expedition in the Arctic regions, 

 the effects of these articles were compared. "After re- 



36. Another property of coffee? Miners of Belgium? The Caravans? 

 A MI ong armies? Taken with meals? 



37. Effects of tea-drinking? Peculiar principle? The tea beverage, how 

 made ? Black and green tea ? Excessive use of tea or coffee ? 



38. Experiments made during Kane's expedition ? 



