t 272 ] 



XIV. UkSirical 'Experiments made In order to a/certain the non- 

 conduct ing Power of a perfeB Vacuum^ &c. By Mr. Wil- 

 liam Morgan ; communicated by the Rev, Richard Price, 

 LL.D. F.R,S. 



Read February 24, IJ^S- 



■^HE iion-condu£ling power of a perfect vacuum is a fade 

 in eledlricity which has been much controverted among 

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

 the double barometer tube clearly demon ftrated the impermeabi- 

 lity of the electric I/ght through a vacuum ; nor was it, 1 think, 

 precipitate to conclude from them the impermeabihty of the 

 eleOincJIuid 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 firfl attended 

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

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

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

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

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

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

 lome phaenomena which appear to be new and interelling. 



A mercurial gage B (fee tab. IX. iig. i.) about 15 inches 

 long, carefully and accurately boiled till every particle of air 

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

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



mercury 



