ON THE PRESENCE OF FUSEL OIE IN BEER. 235 



The illustrious Pasteur found that 100 parts of cane sugar, first 

 •converted into the fermentable variety of sugar, will yield : — 



Ethylic alcohol ... ... ... 48-40 per cent. 



Carbon dioxide ... ... ... 46 - 60 ,, 



Succinic acid ... ... ... '67 ,, 



Glycerine... ... ... ... 3*30 ,, 



Cellulose fat (fee. .. . ... ... 1*20 ,, 



jSTow it is just at this critical stage of fermentation that other 

 higher alcohols may be produced. Pasteur, Schiitzenberger, and 

 Berthelot all recognize the fact of the simultaneous evolution of 

 the higher alcohols under varying, or under abnormal conditions. 

 Schiitzenberger says* : — "We may ask whether these secondary 

 products, [ — i. e, fusel oil] which are relatively not very abundant, 

 owe their origin to alcoholic fermentation properly so called, or to 

 distinct concomitant fermentation having each a special ferment ; 

 or whether, in fact, it is better to attribute their appearance to 

 special principles accompanying glucose in the natural saccharine 

 juices. The actual state of science does not allow us as yet to 

 answer these questions definitely." 



Pasteurf mentions the production of butylic alcohol in irregular 

 fermentation and its non-appearance in carefully conducted 

 fermentation. 



Before proceeding further it will be well to see what is the 

 actual composition of properly brewed genuine beer, so far as it 

 has been investigated by modern chemical research : — 



Percentage composition of genuine beer. 





Dextrin 



:rom 



2 to 5 





Albumenoicls 



55 



•2 — -4 





Maltose 



5) 



1 — 3 





Lactic acid ... 



55 



•02— -05 



Extract^ 



Succinic acid 



55 



•04— 1 





Glycerine 



55 



•2 — -25 





Colouring matter | 





1 — 1-2 





Hop extract j 



55 





Ash (mineral matter) 

 Total Extract 

 weight) 



55 

 55 

 55 



•2 — -27 





5 to 8 



Alcohol (by 



3i to 7 



[Alcohol eqi 



livalent in Proof Spirit 



'5 



7| to 151] 



Acetic acid 





55 



•02 —-04 



Carbonic aci 



d 



55 



•22 —-25 



* Fermentation : Kegan, Paul, French & Co., London, 1S83, p. 30. 

 f Etude sur la Biere, Paris 1878, p. 297. 



