[ 7 8 3 3 
thofe bodies : whereas the glafs tube, when excited 
fo as to emit pencils, will, in a few minutes, electrify 
the air to fuch a degree, that (after the tube is carried 
away), a pair of balls, about the fize of thefmalleft 
peas, turn’d out of cork, or the pith of elder, and 
hung to a wire by linen threads of fix inches long,, 
will repel each other to the diftance of an inch and 
an half, when held at arm’s-length in the middle of 
the room. But their repulfton will decreafe as they 
are moved toward the floor, wainfcot, or any of the 
furniture and they will touch each other when 
brought within a fmall _ diflance of any conductor. 
Some degree of this eleCtric power I have known to 
continue in the air above an hour after the rubbing of 
the tube, when the weather has been very dry. 
The electricity from the clouds, in the open air, 
may be difcovered in the fame manner, if the balls 
are held at a fufhcient diftance from buildings, trees, 
&c. as I have feveral times experienced, by a pair 
which I carry in a fmall narrow box with a' Aiding 
cover, (Fig: 4.) fo contrived as to keep their threads 
ftraight, and that they may be properly fufpended, 
when let fall out of it: and thefe balls will eaftly 
determine whether the electricity of the clouds or air ' 
be pofltive, by the decreafe ; or negative, by the in- 
creafe of their repulfton, at the approach of excited 
amber or fealing-wax. 
To eleCtrify the air, or moifture oontained in it, 
negatively; I Support by filk, between two chairs 
placed back to back, at the diftance of about three 
feet, a tin tube with a fine fewing-needle at one end 
of it ; and rub fulphur, fealing-wax, or the rough glafs 
tube, as near as I can to the other end, for three or 
four. 
