C 415 1 
took a thick piece of pafte-board, acrofs which I 
ruled lines, exactly an .inch afunder„ Upon thefe 
lines, crofs-wife, I placed the wires ; which I 
confined by heavy weights: the edges of which 
weights juft touched the ruled lines; leaving ex- 
a£lly an inch of wire between them [fee tab. xiv.- 
fig. 1.]. The kinds I tried wer pure gold, fiber, 
brafs , copper Jilvered, and iron. They were all drawn 
through the fame hole, except the iron, which 
was fomewhat larger than the others. I proved 
them with two jars, containing eleven fquare feet 
of coated furface ; and adjufted the charges, by 
an eletlrometer graduated in divifions of one tenth 
of an inch each, the diameter of the fcale being 
two inches.. The refult was as follows : 
Pure Gold j • - f 4 j 
Brafs / \ 6 / 
Copper filvered l was melted at < 8 ^ Divifions* 
Pure Silver \ / 1° \ 
Iron J [10J 
If I gave either of the wires a divifion lefs 
than the number above fpecified, it was not 
melted: if I gave either of them a divifion more,, 
it was exploded ; the greater part vanifhing in 
fmoak : whereas thefe charges juft burft them 
into balls. 
Should any gentleman choofe to repeat this 
experiment, I would recommend it to him to 
be very particular in fizing the wires; to life a 
greater length , to do it when they are all frefh 
drawn, to make the experiment in a very dry day, 
and in a room where there is no fire. With thefe 
precautions, probably there may be fome difference 
in the refult; and this method will perhaps give a 
2 true 
