82 ANALYSIS AND ADULTERATIONS OF COFFEE. 



A higher aroma would make the inferior varieties of Ceylon, 

 Jamaica, and Brazilian coffees nearly equal in value to the finest 

 Javas ; and if the oil could be bought for the purpose of im- 

 parting this flavor, it would be worth in the market as much as 

 five hundred dollars an ounce. How it comes by what slow 

 chemical change within the bean, that causes coffee of the most 

 inferior quality so to ripen by keeping as to become equal to 

 Mocha we do not yet know. 



Coffee is supposed to owe its refreshing character to this 

 peculiar chemical principle, Caffeine. This substance belongs 

 to the class of azotized basic bodies, and from its presence in 

 two substances so dissimilar as tea and coffee, both of which 

 are in such general use all over the world, it may be supposed 

 to be of no small importance to our animal economy. Liebig 

 has shown that the composition of caffeine is closely related 

 to that of various animal products, and that there is reason 

 to believe that it may assist in the secretion of bile. A pound 

 of coffee yields by sublimation, on an average, about 15 grains 

 of caffeine. It may also be obtained from an infusion of 

 raw coffee, when certain impurities have been removed by 

 subacetate of lead, and the excess of lead by sulphuretted 

 hydrogen. It forms white silky crystals, which are sparingly 

 soluble in .cold water. It has a mild, bitter taste. The pe- 

 culiarly refreshing and stimulating properties of coffee are 

 developed in the roasting. It has been tested that coffee 

 roasted to a pale brown color loses 12.3 per cent. ; to a 

 chestnut brown, 18.5 per cent. ; and to a black, 23.7 per cent. 



The chemical changes which heat produces in coffee, accord- 

 ing to recent authorities, may thus be epitomized : the brown 

 bitter substance and the aromatic principle are produced by the 

 decomposition of that part of the coffee-bean which is soluble 

 in water; and a large part of the caffeine disappears during 

 the roasting. It is said that this (caffeine) is carried away with 



