CHAPTEE XXII. 



CHEMICAL ANALYSIS OF COFFEE ITS MEDICINAl AND OTHER 



PEOPEKTIES. 



It will prove profitable to examine briefly tbe verdict rendered 

 by cliemistry and physiology respecting the properties of coffee 

 and its so-called substitutes. The researches of scientists inform 

 us that coffee owes its individuality, if I may so term it, to three 

 characteristic constituents : a volatile aromatic oil called caffeone ; 

 an element called caffeine, identical with the theine of tea ; and 

 a kind of tannic acid, analogous to that of tea, called eaffeic acid. 

 Each of these elements possesses virtues and powers of its own, 

 and plays a part in the general effect produced by coffee. 



To the caifeone, or essential oil, which, when chemically sepa- 

 rated by ether, presents the consistency of cocoa-butter, is due 

 the peculiar and delicious aroma given out by coffee in roasting. 

 Taken alone, the oil is found to produce a gentle perspiration and 

 agreeable excitement, and to stimulate the mental faculties, while 

 it retards, in a marked degree, the process of assimilation and, con- 

 sequently, the waste of tissue. It exercises also an aperient effect 

 on the bowels. Over-doses bring on sleeplessness and symptoms 

 of congestion. 



Caffeine, which is inodorous, but has a slightly bitter taste, in 

 creases the nervous activity of the system ; the heart and pulse are 

 quickened, the imagination enlivened. Administered ia stronger 

 doses, it causes trembling and a sort of intoxication, not unlike 

 that resulting from alcoholic stimulants. It is said also to dimin- 

 ish the waste of organic tissue. 



The eaffeic acid, as it exists in the raw bean, has a decidedly 

 astringent tendency. This, however, is modified ia the roasting. 

 and, besides, counteracted by the aperient properties of the caf 



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