118 ALIMENTATION. 



and an infusion of coffee, with milk and sugar, presents > 

 therefore, a considerable variety and quantity of alimentary 

 matter. The peculiar stimulant effects of coffee are prob- 

 ably due to the caffeine and volatile oil. 



The varieties of coffee in common use are very numerous. 

 The best in the market is the Arabian, or Mocha. The 

 characteristic aroma of coffee is developed by age, which im- 

 proves to a very great extent some of the inferior varieties. 

 The best Mocha coffee requires, after it is gathered, three or 

 four years to ripen. In this country and in Europe, coffee 

 is prepared for use by simply making an infusion of the 

 roasted and pulverized berry in hot water, either by boiling 

 or by simple percolation. The aromatic and active prin- 

 ciples are best extracted by the latter process. They are but 

 slightly soluble in cold water. 



An adulteration of coffee, so common as to demand the 

 consideration of the physiologist, consists in the addition of 

 the chiccory-root, cut into small pieces, dried, roasted, and 

 pidverized. This gives a rich brown color to the infusion, 

 and its flavor, not unlike that of coffee itself, is not disagree- 

 able. It has, however, none of the stimulating effects before 

 described ; but is used purposely, to a great extent, by many 

 who do not seek for the peculiar stimulant influence of the 

 pure article. 



In the countries where coffee is grown, the leaves of the 

 shrub, roasted and made into an infusion, are quite com- 

 monly used. Their effects upon the system are similar to 

 those of coffee, and it is said that the natives prefer the leaves 

 to the berry. 1 



Tea. 



An infusion of the dried and prepared leaves of the tea- 

 plant is perhaps as common a beverage as coffee, and taking 

 into consideration its immense consumption in China and 

 Japan, is actually used by a greater number of persons. Its 



1 JOHNSTON, Chemistry of Common Life, New York, 1859, vol. i., p. 157. 



