ANALYSIS AND ADULTERATIONS. 



COFFEE has been analyzed by various chemists, but the results 

 of their analyses are far from being uniform. Raw coffee con- 

 tains a yellowish-brown transparent extract, to which the name 

 of caffeine has been given, and which constitutes the characteris- 

 tic portion of coffee. Coffee also contains a resinous matter, an 

 oil, or fatty substance, an aromatic principle, and some tannin and 

 gallic acid. Six pounds of coffee give ninety grains of caffeine, 

 a proximate principle remarkable for containing 21.54 per cent. 

 of nitrogen, which is a larger quantity than is found in most 

 other vegetables ; it is a crystallizable salt, of a bitter taste, pro- 

 ducing an exhilarating effect when taken in four or five grains, 

 such as is felt when good coffee is drunk. It was first discovered 

 by Runge in 1820, and it is considered by Liebig as nearly iden- 

 tical, if not quite so, with theine, a principle existing in tea. 



Raw coffee contains about five per cent, of an astringent acid, 

 the caffeine, or coffee tonic, which does not blacken a solu- 

 tion of iron, as the infusion of tea does, but renders it green, 

 and does not precipitate solutions of gelatine. This acid is 

 changed to some extent during the roasting, but still retains a 

 portion of its astringent properties, and contributes in some de- 

 gree to the effects which the infusion of coffee produces upon 

 the system. 



But the coffee-bean contains about thirteen per cent, of nutri- 

 tious gluten, which, as in the case of tea, is very sparingly dis- 

 solved by boiling water, and is usually thrown away in the 



