Isolation of Toxic Principles of Coffee. 137 



Second. Persons not affected by coffee drinking, and even 

 accustomed to the vapor given off during the roasting of 

 coffee, have the ordinary symptoms due to the use of coffee 

 through breathing the vapors driven off during the well- 

 known vacuum treatment of coffee, or the roasting of this 

 product. 



Third. Persons unable to drink coffee without suffering the 

 above symptoms are able to drink vacuum-treated coffee with- 

 out suffering in the least. 



M. Burmann also points out that, of the caffeine-containing 

 plants, tea, kola nuts and coffee, the drinks prepared from 

 those richest in caffeine produce the least disagreeable effects, 

 and that coffee, which requires for preparation a process of 

 roasting, produces the most disagreeable effects. 



These and other similar facts prove almost conclusively that 

 some other principle than caffeine is responsible for the toxic 

 effects of coffee. So insistent has been the demands for an ex- 

 planation of the cause of this toxicity that efforts have been 

 made to assign it to the small amount of potassium salts which 

 coffee contains, or to a new alkaloid in the green bean, which 

 has not been isolated. But lately several investigations have 

 been carried on in which an active volatile constituent has 

 been separated from the roasted product. For this reason 

 the fact is fairly well established that the toxic principle, as 

 well as the aromatic principle, is due to the products formed 

 in roasting. In the ordinary process of roasting, the green 

 beans, continually agitated, ^re heated to a temperature vary- 

 ing around 210 C. 



From a consideration of an analysis of green coffee by Ko- 

 nig, the effects of a temperature over 200° C. is quite evident. 



Water 10.73 



Nitrogenous substances 12.64 



Caffeine 1 . 07 



Sugar 8.62 



Other nitrogen-free extractive substances 19.30 



Dextrine 86 



Tannic acid 9 . 02 



Crude fiber 24.01 



J^at 11.80 



Ash 3 . 02 



Of these substances only moisture and caffeine are volatile, 

 but since many nonvolatile vegetable substances decompose 



