go Mr. hetcly’s Experiments and 
of polifhed plate glafs being introduced into the circuit, 
the ends of the wires which compofed the circuit were 
laid at about an inch and an half from each other upon 
the furface of the glafs, when the jar above-mentioned 
being difcharged, the polifh of the glafs was always torn 
off in an irregular and deep line, extending from one 
wire to the other; but if a piece of glafs painted with 
lamp-black and oil were thus introduced into tho cir- 
cuit, and the difcharge made as before, not the fmalleft 
trace of the electricity could ever be perceived on its fur- 
face. 5 thly,.If inftead of the glafsj a flip of writing-paper 
was introduced into the circuit, it was torn in pieces, by 
the explofion, much of.it flying about the room in the 
form of fine flue or down. 6thly, A flip of the fame 
paper, painted with lamp-black and oil, received not the 
leaf! injury, nor fhewed the fmalleft trace of the electri- 
city upon its furface but the common oiled paper, with- 
out lamp-black, was torn confiderably, though not fo 
much as the paper unoiled !t K When the charge of the 
jar above-mentioned is made to pafs between the furface 
{ b ) Mr. cavallo, who hath fince repeated thefe experiments, finds, that 
if the paper be very thinly painted with the lamp.rblack and oH, it will be torn 
by the explofion;,; but having tried a piece of the fame that I had ufed in ray 
experiments,, he was not able to make the leaft impreflion on it. Lamp-black 
and tar therefore, on account of the greater tenacity of the latter, and its being 
equally a non-conduflor, feems to be the moft proper for thepurpofe. 
of 
