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XIV. Electrical Experiments made In order to af cert am the non- 

 cotiducti?ig Power of a perfeSl Vacuum^ &c. By Mr, 'Wil- 

 liam Morgan ; communicated by the Rev. Richard Price, 

 LL.D, F.R.S, 



Read February 24, i"]^S* 



THE non-condu£ling power of a perfect vacuum is a fa£t 

 in electricity which has been much controverted among 

 philofophers. The experiments made by Mr. Walsh, F.R.S. in' 

 the double barometer tube clearly demonftrated the impermeabi- 

 lity of the eledtric light through a vacuum ; nor was it, 1 think, 

 precipitate to conclude from them the impermeability of the 

 c\cd:nc Jluid itfelf. But this conclufion has not been univerfally 

 admitted, and the following experiments were made with the 

 view of determining its truth or fallacy. When I firft attended 

 to the fubje6l, I was not aware that any other attempts had 

 been made befides thofe of Mr. Walsh; and though I have 

 iince found myfelf to have been in part anticipated in one of 

 my experiments, it may not perhaps be improper to give fome 

 account of them, not only as they are an additional teftimony 

 in fupport of this fa6l, but as they led to the obfervation of 

 fome phaenomena which appear to be new and interefting. 



A mercurial gage B (fee tab. IX. fig. 1.) about 15 inches l_ 

 long, carefully and accurately boiled till every particle of air 

 was expelled from the infide, was coated with tin-foil five 

 inches down from its fealed end (A), and being inverted into 



mercury 



