240 ON THE PRESENCE OF FUSEE OIL TX BEER. 



Hops contain about 7 J parts in a thousand of an essential oil. 

 This oil consists of a terpene isomeric with turpentine oil (C 10 

 H 16 ) and a stearoptene termed valerol (C 6 H 10 O ?) : the first, 

 being a very volatile etherial body, is entirely dissipated during 

 the process of brewing and gives that pleasant aromatic odour often 

 noticed in the brewery ; the second consists of a mixture of the 

 stearoptene valerol and resin. The valerol is easily oxidised by 

 ordinary atmospheric oxidation into valeric acid, which may 

 sometimes be observed in the peculiar cheesy smell of old hops. 



Yalerol being soluble in ether and in ethylic alcohol would 

 therefore be found in the crude chloroform extract ; hence the 

 necessity for a prolonged washing with water to remove both the 

 valerol as well as the ethylic alcohol before proceeding further 

 with the process. If the impure and unwashed chloroform residue 

 be oxidised the valerol would become oxidised into valeric acid 

 along with the amylic alcohol. The presence of the hop oil of the 

 hops may therefore be recognised if the chloroform residue be 

 divided into two parts : one of which is thoroughly washed and 

 oxidised by chromate. If oxidation yields valeric acid in the one 

 case and none in the other, then it follows and, I think proves 

 conclusively that hops have been used in brewing the beer. 



The process, therefore has a double value and significance ; 

 namely, in determining first, whether the beer has been really 

 flavoured with hops, and secondly if the higher alcohols are present. 



To remove all doubt as to whether the fusel oil really existed 

 in beer, I took two litres of beer and removed the whole of the 

 ethylic alcohol by slow and careful evaporation ; the liquid was 

 made alkaline by sodium hydroxide treated with ether in a 

 separator and the valerol thus removed. Acetic acid was then 

 added to neutralise the soda and the chloroform process, as before 

 described and carried out. The result was that barium valerianate 

 was produced as before. This was dissolved in water with a few 

 drops of nitric acid, the barium estimated as sulphate and the 

 amount of fusel oil found and expressed in terms of amylic alcohol. 



Four and a-half litres of beer ( = 1 gallon) gave *530 grain of 

 barium sulphate, equal to '4 grain of amylic alcohol per gallon. 



One gallon of another sample gave on analysis -324 grain of 

 barium sulphate, equal to -245 grain of amylic alcohol per gallon. 



In another instance, one gallon of a beer gave 1*18 grain of 

 barium sulphate equal to *89 grain of amylic alcohol per gallon, 

 this being the largest proportion found. The amount therefore of 

 fusel oil ranged from \ grain to nearly 1 grain ['245 to *89] per 

 gallon. 



Molecular weight of C, H xl HO = 88 

 ditto . C 6 H 9 2 H=102 



