154 ALIMENTATION 



and is not followed by reaction or unpleasant after-effects. Habitual 

 use renders coffee almost a necessity, even in those who are otherwise 

 well nourished and subjected to no extraordinary mental or bodily 

 strain. Taken in excessive quantity, or in those unaccustomed to its 

 use, particularly at night, it may produce persistent wakefulness. These 

 effects are so well known that it is often taken for the purpose of 

 preventing sleep. 



It has been shown that the use of coffee permits a reduction in the 

 quantity of food, in workingmen especially, much below the standard 

 that would otherwise be necessary to maintain the organism in proper 

 condition. In the observations of De Gasparin on the regimen of the 

 Belgian miners, it was found that the addition of a quantity of coffee to 

 the daily ration enabled them to perform their arduous labors on a diet 

 which was even below that found necessary in prisons where this article 

 was not used. Experiments have shown, also, that coffee diminishes 

 the absolute quantity of urea discharged by the kidneys. In this respect, 

 so far as has been ascertained, the action of coffee is like that of alco- 

 hol ; and it may reasonably be supposed to retard katabolism, with the 

 important difference that it is followed by no unfavorable after-effects 

 and can be used in moderation for an indefinite time with advantage. 



Coffee usually is roasted before an infusion is made. During this 

 process, the grains are considerably swollen, but they lose sixteen or 

 seventeen per cent in weight. A peculiar aromatic substance also is 

 developed by roasting. If torrefaction is pushed too far, much of 

 the agreeable flavor of coffee is lost, and an acrid empyreumatic sub- 

 stance is produced that is disagreeable to the taste. 



Tea. An infusion of the dried and prepared leaves of the tea-plant 

 is perhaps as common a beverage as coffee ; arid taking into considera- 

 tion its large consumption in China and Japan, it actually is used by a 

 greater number of persons. Its effects on the system are similar to 

 those of coffee, but they usually are not so marked. Ordinary tea, 

 taken in moderate quantity, like coffee, relieves fatigue and increases 

 mental activity, but does not usually produce such persistent wake- 

 fulness. 



Both tea and coffee contain peculiar organic substances. The active 

 principle of tea is called thein, and the active principle of coffee, caffein. 

 As they are supposed to be particularly efficient in producing the pecul- 

 iar effects on the nervous system characteristic of both tea and coffee, 

 there is good reason to suppose that they are nearly identical in their 

 physiological action. Analyses have shown that thein, or caffein 

 (C 8 H 10 N 4 O 2 4- H 2 O), exists in greater proportion in tea than in coffee ; 

 but as a rule, a greater quantity of soluble matter is extracted in the 



