Alcoholic strength from specific gravity

Determination of the Alcoholic Strength from the Specific Gravity.—The specific gravity of the alcoholic liquid is first determined by means of the apparatus here described and the alcoholic strength then deduced as described later (p. 236). 

The alcohol is determined either by distilling the wine and calculating from tables the alcoholic content of the distillate from its specific gravity at 150 C. or by means of a special apparatus known by the name of ebullio-scope. This gives the alcoholic degree of the wine with sweet wines, a calculation is sometimes also made of the potential alcoholic strength, which is the sum of the alcohol found and of that derivable from the fermentation of the sugars still present.1... 

Procedure. Into a separating funnel of about 300 c.c. capacity are introduced successively 50 grams of recrystallised and finely powdered common salt, 200 c.c. of the alcoholic distillate brought to about 25% strength and 10 c.c. of petroleum ether of b.pt. about 40° C. The whole is shaken until the salt is completely dissolved and then for about ten minutes longer. In this salt solution the essences are almost entirely insoluble and they are dissolved in the petroleum ether, which is easily separated from the salt liquid owing to the marked difference in specific gravity. 

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