EXAMINATION OF VQLTa's EXPERIMENTS, &C. 281 



When the hydrometer is intended only for fpirituous com- Applicable to 

 pounds, the weights are applied lingly as beicre-mentioned : J^ r Jhe wefuhu' 

 if, however, in addition to the weight No. 4, the others are doubly, 

 fucceffively applied, it becomes applicable to the examination 

 of worts and other liquors, whofe fpecific gravities are from 

 1.000 to 1.109, or, in the language of the brewery, up to Spec. gr. of 



„ , , , . ° ° T , . ., ., ,, worts defignated 



40 lbs. per barrel heavier than water. In this cale the other by lbs# per bar _ 



three (ides of the flem are alfo graduated, and another rule re!. 



with an ivory Aider, carrying a thermometrical fcale for com- for tbe brewery# 



paring worts at different temperatures, is included in the cafe 



with the inftrument. 



The writer of this paper having made a confiderable number 

 of experiments with this inftrument, on the fpecific gravities of 

 a variety of fpirituous liquors, had originally intended to have 

 given their refults ; but it has already run to fuch a length, that 

 they mud be deferred to a future communication. The errors, Errors in refultt 

 even including thofe which mud neceffarily arife from the va- v " y fmall > * n< * 



& ■> advantage of 



rious temperatures of the compounds, and the different quanti- facility ofufe 



ties of foreign matters with which thefe fluids, in an impure very confider- 



fiate, may be fuppofed to be charged, appear to fall within 



very narrow limits ; and the extreme facility and expedition 



with which it refolves the, queftions to the folution of which it 



is applicable, cannot fail to render it very highly valuable to 



thofe for whofe purpofes it is principally intended. 



XIV. 



An Examination of Sig. Volta's Experiments- which he calls 

 fundamental, and upon which his Theory of Galvanifm refts ; 

 with a Defcription of a very fenfibk Elecliical Condenfer, and 

 an Explanation of the Action of the Eleclric Fluid in the 

 Galvanic Inftrument. By John Cuthbertson, Philo- 

 fophical Inftrument Maker, No, 54, Poland Street, London* 

 Communicated by the Author, 



In Vol. I. 8vo, page 136, paragraph three, of this Journal, ^'con^of^ 

 Sig. Volta affirms, " If two infulated difes, one of copper andinfulated difesof 

 " the other zinc, be applied together for a moment and then co P per . and ^ ,1C . 



, , . , producing + el. 



" leparated, the zinc will be pofitive and copper negative." in the zinc, and 

 I have always had the fame refult, but fome times much~" e1, ,n the 

 weaker than at others. Succeeds. 



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