[ 2 7 2 ] 
XIV. 'Electrical Experiments made in order to af certain the non - 
conducting Power of a perfect Vacuum , &c. By Mr. Wil- 
liam Morgan ; communicated by the Rev. Richard Price, 
HE non-conduding power of a perfed vacuum is a fad 
in eledricity which has been much controverted among 
philofophers. The experiments made by Mr. W alsh, F.R.S. in 
the double barometer tube clearly demon ft rated the impermeabi- 
lity of the electric light through a vacuum ; nor was it, 1 think, 
precipitate to conclude from them the impermeability of the 
eledric fluid itfelf. But this conclufion has not been uni verfally 
admitted, and the following experiments were made with the 
view of determining its truth or fallacy. When I frit attended 
to the fubjed, I was not aware that any other attempts had 
been made befides thofe of Mr. Walsh ; and though I have 
fince 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 fad, but as they led to the obfervation of 
fome phenomena which appear to be new and interefting. 
A mercurial gage B (lee tab. IX. fig. i.) about 15 inches 
long, carefully and accurately boiled till every particle of air 
was expelled from the inlide, was coated with tin-foil five 
inches down from its lealed end (A), and being inverted into 
LL.D. F.R.S. 
Read February 24, 1785. 
mercury 
