ON THE PRESENCE OF FUSEL OIL IN BEER. 239 



together with 50 cb. c. of chloroform ; after repeated shaking, the 

 liquid is allowed to subside, and the beer poured off without 

 disturbing the chloroform. More beer is added until half the 

 gallon has been so treated, when a further 50 cb. c. of chloroform 

 is added together with more of the beer until about 5 pints have 

 been used ; a third 50 cb. c. is taken, making altogether 150 cb. c. 

 of chloroform with which the remainder of the beer is thoroughly 

 agitated. By this time the whole of the fusel oil will have been 

 extracted. The next step is to wash the chloroform with water 

 to remove traces of valerol derivable from the hops, and also to 

 remove ethylic alcohol that may have been taken up into solution. 

 The solution is then placed in a strong glass vessel with 5 grams. 

 of potassium di-chromate and 2 grams of concentrated sulphuric 

 acid and oxidised under pressure for six hours at a temperature 

 of 85 D C. The oxidation having been completed, the liquid is now 

 distilled, water added to the residue and the distillation continued. 

 The distillate, which has a strong odour of valerianic acid is boiled 

 for half an hour with some pure barium carbonate in a flask 

 connected with an inverted Liebeg condenser. After this the 

 chloroform is removed by distillation and the residue filtered. 

 The filtrate is then evaporated to dryness in a platinum dish, 

 weighed and dissolved in water with a few drops of nitric acid. 

 The solution is divided into two equal parts. In one the barium 

 is estimated : in the other the amount of barium chloride. The 

 weight of the latter is deducted from the residue. The total 

 amount of barium salt, minus that existing as chloride, gives the 

 amount of barium as barium valerianate and from which the 

 amount of amylic alcohol is readily found. 



The chloroform and the rectified' spirit used throughout this 

 research was carefully tested by blank experiments for the presence 

 of the higher alcohols. Care was taken that only pure chloroform 

 was used. 



Another method for the estimation of minute quantities of 

 amylic alcohol, and indeed for all the higher alcohols is that of 

 Traube,* who employ" a method based on the fact that butylic 

 and amylic alcohols depress the capillarimetric -column in a small 

 tube. This process has in my hands been found more suitable for 

 brandies and white spirits than for beer. 



During the first experiments in working out this process, a 

 somewhat unlookecl for result was obtained ; one giving positive 

 indications that genuine hops had been used in the brewing of all 

 the samples of Sydney beer ; thus corroborating the results I 

 obtained by the methods of Dupre and Allen used in my search 

 for spurious bitters and hop-substitutes. 



* Bulletin de la Societe chimique de Paris. 



