MALT LIQUO&S. 283 



METHODS OF ANALYSIS. 



In the work on malt liquors an endeavor has been made to simplify 

 the analyses as much as possible, and various methods have been tried 

 with this end in view. The various processes given are believed to be 

 the best possible for combining rapidity of execution with sufficient ac- 

 curacy of results. 



The necessary determinations may be conveniently divided into two 

 classes : 



1. The analysis of the sample proper, comprising determination of 

 the density, alcohol, extract or total solids, original gravity, saccharine 

 matter, albuminoids, free acid (fixed), free acid (volatile), ash, glycerine, 

 phosphoric acid, and carbonic acid. 



2. The processes for the detection of adulteration, comprising a search 

 for substitutes for inalt, substitutes for hops, preserving agents (sali- 

 cylic acid, borax, sulphites), and mineral additions. 



ALCOHOL. 



The estimation of alcohol in beers and wines is generally made in 

 one of two ways, either by direct distillation and determining the 

 alcohol in the distillate, or, indirectly, by evaporating the alcohol from 

 a sample and obtaining the per cent, from the difference in specific 

 gravity of the sample before and after the alcohol has been driven off. 

 Authorities differ as to the accuracy of the indirect method, some even 

 holding it to give better results than the direct estimation. It is gen- 

 erally recommended to use both methods, as the one gives a check 

 over the other, and it is very easy to carry bath on together, as the 

 same sample which is used for the distillation can be used for the de- 

 termination of the density of the de-alcoholized solution, provided no 

 tannin is used. I much prefer the distillation method, and have adopted 

 the results by it in the tables. 



I have almost invariably found that during the distillation a precip- 

 itation of flocculent albuminous matter takes place in the flask, evi- 

 dently bodies which are rendered insoluble, either by the evaporation of 

 the alcohol or acetic acid, or by the heating of the solution, and it would 

 seem obvious that this separation of solids from the solution would 

 vitiate more or less the results by the indirect method. 



For the distillation method lOOcc. of the sample, freed from carbonic 

 acid by shaking, are measured out, rinsed into a flask with about 50cc. 

 water, the latter connected with a Liebig's condenser, and lOOcc. dis- 

 tilled off. The sample and distillate should be measured at the same 

 temperature. The specific gravity of the distillate is then obtained 

 by means of an accurately tared picnoraeter, preferably one carrying a 

 thermometer, so that the weight maybe taken at exactly 15.5 C. The 

 per cent, of alcohol in the distillate is then obtained by reference to a 

 table giving the per cent, of alcohol in solutions of different specific 



