238 ON THE PEESENCE OF FUSEL OIL IN BEEK. 



itself that such is the case, the brewer must first convert them 

 into a fermentable variety of sugar ; the sugar must be inverted 

 as it is more correctly termed. Cane sugar of itself is unfermental )le. 

 This inversion may be effected in four different ways : — 



1. By malt extract in mashing at not too high a temperature. 



2. By prolonged boiling with water. 



3. By treatment with yeast and water. 



4. By the action of sulphuric acid and after treatment 



with chalk. 



The brewer is confronted with the question as to what sugar 

 may be used, raw or refined crystals ? If the former, other 

 organisms besides the S. cerevisice would inevitably be introduced : 

 this would be followed by a high and uncontrollable fermentation r 

 with refined crystals the sugar we have seen, has to be inverted. 

 Another question then arose, were these beers brewed at an 

 abnormally high temperature ? Remembering that an eminent 

 authority on brewing, Dr. Charles Graham, had found that a high 

 temperature in fermentation means not only a rapid attenuation 

 of the wort, but an increased loss of alcohol by evaporation, together 

 with an increase in the higher alcohols — the fusel oils ; reasoning 

 upon this hypothesis the presence of fusel oil would therefore 

 indicate to some extent the mode of manufacture of the beer. The 

 question then resolved itself into this — does this beer contain 

 fusel oil % Some difficulty then arose as to the process for finding 

 out whether higher alcohols existed in beer. The methods in use 

 which were applicable to liquids, such as brandy and whisky, 

 failed when applied to beer. The method of fractional distillation 

 was tried : the distillates from two litres of beer were placed in a 

 flask fitted with a modified Henipel's column and the fractions 

 collected separately, a current of steam being used to remove the 

 last traces. As the boiling points of the different alcohols were 

 not sufficiently marked from each other, the idea presented itself 

 of converting the alcohols into their respective iodides, since the 

 boiling points would be sufficiently removed from each other to 

 enable a more complete separation to be effected. 



However, these methods were afterwards abandoned, since it 

 might be said that these higher alcohols might be generated in the 

 act of distillation, an objection that I do not think carries much 

 weight, as the alcohols are products of fermentation and are not 

 likely to suffer changes in distillation. ' However, these methods 

 were set aside for a process that would remove the higher alcohols 

 from the beer itself, without distillation. The process I finally 

 adopted — a modification of my own of Marquardt's — was based 

 upon the fact that amylic alcohol is soluble in chloroform. 

 I operated on a gallon of the beer in the following manner : — 

 Some of the beer to be tested is placed in a capacious separator, 



