CHEMICAL ANALYSIS OF COFFEE. 175 



In another form, according to Payen, tlie analysis of unroasted 

 coffee gives the following results : 



Water 12.00 



riesh-formers 14. Y5 



Heat-givers 66.25 



Mineral matter 7.00 



100.00 



The Jov/rnal of Pharmaceutical CheTrdsbry contains the fol- 

 lowing in relation to the experiments of Dr. C. O. Cech, of St. 

 Petersburg, upon the oil of roasted coffee : 



" Although the coffee-bean belongs to our daily food, we are 

 stiU uncertain of the chemical nature and composition of the pro- 

 ducts of roasting coffee, and of oil of coffee, one of the important 

 characteristic constituents of the bean. The existence of a coffee 

 oil makes itself known in a striking manner by its roasting, for 

 this oil, driven out of the beans by the heat, is partially vola- 

 tilized, and, together with other products of the roasting, produces 

 the characteristic aroma of roasted coffee, an odor possessed by no 

 other substance. In very strong black coffee, too, we can see this 

 oil like little drops of grease floating on it. The amount of oil in 

 coffee varies from eight to thirteen per cent., and at least half of 

 this is lost in roasting, so that it would be a paying experiment to 

 attempt to collect this oil, especially in large establishments where 

 much coffee is burned and several pounds of oil are dissipated 

 daily. In 1878, not less than five hundred thousand tons of coffee 

 were consumed, so that the amount of oil that might have been 

 collected was very considerable. Dr. Cech tried the experiment, 

 in one of the large roasting estabhshments of Berlin, of connect- 

 ing the roasting drum with a cooling apparatus and a receiver, so 

 as to condense and collect the volatile and oily products of the 

 roasting. At first there is scarcely any gas generated in the 

 drums, but after the beans are browned and the whole mass has 

 been heated to the temperature where the oil evaporates, such a 

 quantity of the volatile aromatic oil is generated that it trickles 

 down the walls of the chamber in which the beans are shovelled 

 and cooled after coming from the drums. Unfortunately, the 



