392, Mr. cavallo’s Experiments and 
meter inftantly diverges with ftrong negative elec- 
tricity. 
I repeated the above experiments with this only dif- 
ference in the difpofition of the apparatus: I put the 
electric plate with the excited fealing-wax upon the 
circular tin-plate, and the glafs uppermoft : and the dif- 
ference in the refult was, that where the electricity was 
poiitive in the former difpofition of the apparatus, it now 
became negative, and vice verja\ except that, when I 
firft lay the eleCtric plate upon the tin plate, the electro- 
meter diverged with negative electricity as well in this 
as in the other difpofition of the apparatus. 
All the above experiments have been repeated with 
an eleCtric plate, which, befides the fealing-wax coating 
on one fide, had a ltrong coat of varnifh on the other; 
and their refult has been fimilar to thofe when the above 
defcribed plate was ufed. 
Experiments on colours . 
Having accidentally obferved that an eleCtric Shock, 
fent over the furface of a card, marked a black ftroke 
upon a red fpot on the card, I was from this induced to 
try what would be the effeCt of fending Shocks over 
cards painted with different water colours. Accordingly 
4 I painted 
