A rapid process for determining the proportion of alcohol in a liquid has been described by D. Sidersky.1 It depends upon the miscibility of ether with strong alcohol.

Twenty c.c. of the alcoholic liquid under examination and 10 c.c. of ether, sp. gr. 0.724, are shaken in a closed vessel. On standing, the liquids separate into two layers. Successive quantities of alcohol (98 per cent.) are now added from a special burette, the mixture being shaken between each addition. The volume of the ether.alcohol layer decreases as the proportion of alcohol increases, until it finally disappears on addition of a further drop of alcohol.

1 Bull. Assoc. Chim.Sucr., 1909, 27, 562.

The total amount of alcohol which will cause the solution of the ether under these conditions is determined once for all by preliminary experiments. Deducting the amount run in from the burette gives the quantity in the 20 c.c. of liquid dealt with.

The burette used is so graduated as to show the percentage of alcohol in the sample directly. The vessel used for the mixing has a narrow neck, to facilitate observation of the two layers, (Patented; H. Rapeller.)