ALCOHOLOMETERS. 



181 



po-wers of sucli quantities of grape-sugar solution, kept for a 

 long time, of freshly dissolved grape-sugar, of starch malt- 

 sugar, and of dextrine, as will all give the same quantity of 

 alcohol, are in the ratio of 1 : 2 : 3 : 4. (Journ. Prac. Chem. 

 xlii. 418.) 



AlcoJiol and Water. — Townes gives the following results of 

 his experiments to determine the specific gravity of mixtures 

 of alcohol and water. Column A shows the percentage of 

 alcohol by weight in the mixture, and B the spec. grav. at 60°. 



AlcoJiolometers. — Two instruments have been invented for 

 determining the proportions of alcohol in liquids containing 

 substances in solution which increase the spec. grav. of the 

 liquids, in whicli case the indications of a hydrometer are not 

 to be relied on. The principle of their use depends upon the 

 lower boiling point of a mixture in proportion to the quantity 

 of alcohol it contains. They are termed EhulUoscopes. The 

 instrument employed by Brossard-Vidal is a large thermome- 

 ter ; the mercury in the tube carrying a float, from which a 

 cord passes over a pulley and is counterpoised by a light 

 weight. An index is attached to the roller, which points to 

 degrees on a graduated scale, according as the pulley revolves, 

 i. e. as the level of mercury alters, when the liquid boils. 



Conaty's instrument is a common thermometer, with a scale 

 attached, which directly indicates the proportion of alcohol 

 contained in a liquid into which it is immersed during ebulli- 

 tion. The movable scale may be also adjusted for barometric 

 variation, so that further corrections are avoided. Both in- 

 struments have been reported to the Paris Academy as capable 

 of* indicating 1 or 2 per cent, of alcohol in a liquid, but that 

 of Conaty is thought to be the most convenient. (Comptea 

 Rendus, xxvii.) 

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