254 



CHEMICAL CONSTITUENTS. 



the former exercising a sedative and tranquilizing action, 

 being more prolonged in its effect than the latter, which 

 acts strongly as a transient stimulant and exhilarant. 

 But in the drinking of an ordinary cup of coffee both 

 these actions are obtained, the stimulation and exhilara- 

 tion preceding the state of sedation and repose. The 

 essential principle of the coffee, however, is the alkaloid 

 caffeine and not the volatile oil caffeone, the effects 

 of both constituents being different in time and character- 

 The former slows the heart's action and expends its 

 main force on the spinal cord, to which effect is due the 

 shaking hand of the inveterate coffee-drinker and the 

 marked tremor which sometimes follows a copious 

 drink of coffee when taken on an empty stomach, while 

 the latter reduces the arterial tension, thereby allowing 

 a freer flow of blood and a more rapid action of the heart, 

 at the same time stimulating the brain, rendering the 

 mind clear and promoting wakefulness, being also speedier 

 and more transient in effect. 



Gaffcic. — Caffetannate, or " tannic acid," as it exists in 

 the raw bean of coffee possesses an astringent action, which 

 is greatly modified in the roasting and neutralized by 

 the aperient properties of the Caffeone. A great deal 

 of doubt still exists as to the exact agency of this 

 property in coffee, many chemists contending that to it 

 the flavor and other properties of the coffee as a bever- 

 age is due. It is a powerful astringent principle, puck- 

 ering up the mouth when chewed, and is the property to 

 which coffee owes its bitterness when boiled or over- 

 infused, but whether it contributes in any degree to the 

 exhilarating, satisfying or narcotic action of the coffee 

 has not yet been definitely determined. But united, 

 their specific properties modified by combination and 



