180 



ALIMENTATION. 



It is unnecessary to describe all the varieties of tea in common use 

 There are, however, certain varieties, called green teas, which present impor- 

 tant differences, as regards composition and physiological effects, from the 

 black teas, which latter are more commonly used. The following is a com- 

 parative analysis of these two varieties by Mulder : 



Both tea and coffee contain peculiar organic substances. The active prin- 

 ciple of tea is called theine, and the active principle of coffee, caffeine. As 

 they are supposed to be particularly efficient in producing the peculiar effects 

 upon the nervous system which are characteristic of both tea and coffee, there 

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

 effects. Analyses more recent than the one quoted from Mulder (Stenhouse, 

 Peligot) have shown that theine, or caffeine (C 8 H 10 N 4 2 + H 2 0), exists in 

 greater proportion in tea than in coffee ; but as a rule, a greater quantity of 

 soluble matter is extracted in the preparation of coffee, which may account 

 for its more marked effects upon the system. Some analyses have given as 

 much as six per cent, as the proportion of theine in tea (Landois). 



Chocolate. Chocolate is made from the seeds of the cocoa-tree, roasted, 

 deprived of their husks, and ground with warm rollers into a pasty mass with 

 sugar, flavoring substances being sometimes added. It is then made into 

 cakes, cut into small pieces or scraped to a powder, and boiled with milk or 

 milk and water, when it forms a thick, gruel-like drink, which is highly 

 nutritive and has some of the exhilarating properties of coffee or tea. Beside 

 containing a large proportion of nitrogenized matter resembling albumen, 

 the cocoa-seed is particularly rich in fatty matter, and contains a peculiar 

 substance, theobromine (C 7 H 8 N 4 2 ), analogous to caffeine and theine, which 

 is supposed to possess similar physiological properties. 



The following is an analysis by Payen of the cocoa-seeds freed from the 

 husks but not roasted. Torrefaction has the effect of developing the pecul- 

 iar aromatic principle, and of moderating the bitterness, which is always more 

 or less marked : 



