284 FOOD AND FOOD ADULTERANTS. 



gravities, of which tables llehner's are the best in use. This per cent, 

 multiplied by the specific gravity of the distillate, and the result di- 

 vided by the specific gravity of the original sample, gives the per cent, 

 of alcohol by weight contained in the latter. The accuracy of the oper- 

 ation is increased by weighing the sample taken, and also the distillate. 

 Then the weight of th ) distillate multiplied by the per cent, of alcohol 

 corresponding to its specific gravity as found in the table, and the re- 

 sult divided by the weight of the sample taken, gives the per cent, of 

 alcohol by weight contained in the laitter. 



For the indirect method it is necessary to estimate accurately the 

 specific gravity of the original beer, thoroughly freed of carbonic acid 

 by shaking and standing; then lOOcc. or any convenient quantity is 

 measured out, evaporated to half its bulk, cooled, and made up to its 

 original volume with water, taking care to have the solution at the same 

 temperature as the sample when first measured. The specific gravity 

 of the de alcoholized liquor is taken. Then the specific gravity of the 

 original sample divided by the specific gravity of the de-alcoholized 

 solution gives the specific gravity of the alcohol evaporated, from which 

 figure the per cent, of alcohol is ascertained by reference to the table. 

 The same sample which is used for distilling can be very conveniently 

 used for this determination as well. 



