128 Mr. henly’s Experiments and 
hitherto warmed the fubftances, but kept the rubber 
cold ; fufpefting that, in fome cafes, the refult might be 
different from what it is when the rubber is warm and 
the fubftance cold: but this, with the effect of cloths of 
different textures and colours, filks, fattins, velvets, lea- 
ther drefled in oil, and in allum, &c. ufed as rubbers, I 
have not had leifure to determine. A fmall turnip and a 
potatoe, which I could not excite at all with either of the 
rubbers when they and the fubftances were cold, I ex- 
cited in a very fmall degree with the flannel a little 
warmed ; but very ftrongly when the flannel and the re- 
fpective articles were, each of them, moderately warm. 
A fprig of celery ailed very powerfully when the 
flannel only had been previoufly warmed <k] . As in all 
cafes the rubber is affeited with an electricity contrary 
to that of the fubftance rubbed, it will be fufficient for 
oyer the back of a cat, or by exciting it with a dry, warm rabbit’s fkin ; that 
a fmall coated bottle may be charged with a flip of writing-paper, excited by 
drawing it brifkly between the fingers of a dry hand lo as to pierce a hole in a 
card; that the dry leathern cover of a book may be m .de ftrongly electrical by 
the frlCtion of a dry hand, and that its eleCtricity is remarkably fhewn by 
touching it with an infulated button, in the form of the plate to Mr. volta’s 
machine. He then acknowledged, that fuch an objection as he had darted muft 
certainly be groundlcfs. 
(k) A palma-chrijii nut was excited very ftrongly with the flannel, weakly 
with my coat, and not ail (in a room where there was no fire) with the black 
filk. I have alfo to add, that fome particular fubftances, though negatively 
eleCtrical when heated, become pofitive when cold, by friction againft the very 
fame rubber. 
many 
5 
