"Obfervatiom in EleSIricity. 1 17 
■-nifhed, and in a fhort time ahnoft totally ceafed: this, 
5 think, clearly indicates that the electricity in the lower 
.furface of the glafs and the table were mutually affeCted 
in the operation, as well as that, in the excited fealing-wax 
and the brafs plate (h) . 1 have feen one of thefe machines, 
made by Mr. cavallo, aCt fo fkrongly that, -upon fepa- 
rating the brafs plate from the fealing-wax, a flafh has 
ftruck from 'the brals toward the table, and it has betides ' 
given a ftrong fpark upon the knuckle, when held at up- 
wards of an inch diftance. If the brafs plate, after being 
.raifed from the wax, be prefented with - its edge toward 
the wax (lightly touching it) and thus drawn over its 
furface, the electricity of the plate, he obferves, will be 
abforbcd by the fealing-wax, clearly fhewing the ftrong 
negative ftate in which the excited wax is left on the re- 
moval of the brafs plate. 
The attraction between the plates is alfo fometimes fo 
ftrong, that the coated glafs has frequently been lifted 
up by the’ brafs plate from the table ; yet in a few days, 
being carefully placed in a proper repofitory.(in contaCt 
with each other) not the leaft fign of electricity has been 
( h ) It has beea fuppofed by fame gentlemen, that the very fame quantity .of 
eleCtricity imparted by. the linger to the plate on touching it, was emitted again 
by the plate on removing it from the electric and prefenting it towards the 
knuckle; and that therefore, in air perfectly dry, this machine would at all 
times exhibit its phenomena, without a. frefh excitation of the eleCtric, and 
thus merit the appellation of a machine for exhibiting perpetual electricity-; but 
the faCt a !>eve mentioned entirely refutes that fuppohtiom 
2 'difcoverable 
