CHEMICAL EXAMINATION OF RAW MATERIALS. 199 



the determination of the actual content of alcohol in a fluid whose 

 temperature is above or below the normal temperature (59 F.). 

 For the purpose of examining fluids with a very small content 

 of alcohol, alcoholometers have been constructed which accurately 

 indicate at least 0.1 per cent. For the demands of the fabrica- 

 tion of vinegar, four alcoholometers will, as a rule, suffice ; they 

 should be so selected that one is to be used for fluids with from 

 to 4 per cent, of alcohol, the second for indicating 4 to 8 per 

 cent., the third 8 to 12 per cent., and the fourth 12 to 16 percent. 

 The scale of such alcoholometers comprising only 4 per cent, each, 

 is sufficiently Targe to allow of the easy reading off of one-tenth 

 per cent. These instruments serve for the determination of the 

 content of alcohol in alcoholic liquid consisting only of spirits of 

 wine and water, and are used in examining the progress of the 

 formation of vinegar during fabrication. 



Determination of the Alcohol by the Distilling Test. 



The content of alcohol in a fluid containing other bodies be- 

 sides .alcohol and water cannot be directly determined by means 

 of the alcoholometer, as the statement of the latter would be in- 

 correct on account of the foreign bodies exerting a considerable 

 influence upon the specific gravity. Hence, the content of alcohol 

 in alcoholic liquid containing a certain quantity of acetic acid, or 

 of fermented whiskey-mash, beer, wine, etc., cannot be ascer- 

 tained by immersing the alcoholometer in the respective fluid. In 

 order to determine the content of alcohol in such a fluid a deter- 

 mined volume of it is subjected to distillation and the latter con- 

 tinued until it may be supposed that all the alcohol present is 

 volatilized and again condensed in a suitable cooling apparatus. 

 By diluting the fluid distilled over with sufficient water to restore 

 it to the volume of the fluid originally used and immersing the 

 alcoholometer the content of alcohol is determined. 



A rapid and at the same time accurate execution of all exami- 

 nations being of great importance in practice, a suitable apparatus 

 should be used for the distilling test. Such an apparatus is 

 shown in Fig. 43. It consists of a glass boiling flask, K, having 

 a capacity of J liter in which sits by means of a perforated 



erm 



