Obfervations in Electricity. 137 
the American aloe w , being rubbed upon new, fine, cla- 
ret-coloured cloth, became weakly electrified pofitively. 
A lock of black hair from a young colt I have ob- 
ferved to become very weakly electrified negatively, 
when excited either with wool or filk. 
It will be proper to obferve, that the rubber of wool- 
len cloth, which I ufed in the preceding experiments, 
was a part of the coat or waiftcoat which I happened to 
wear at the time ; but being defirous to try the effeCt of 
another, I took a piece of fine, new, white flannel, and 
ufing that fide of it which is free from knap, I perceived 
a remarkable difference; viz. the copper and other but- 
tons, the different ftones,, fliells, China ware, mofi of the 
animal fubftances (hair excepted) and all the vegetable 
ones, which with the former rubbers were pofitively, 
being now negatively electrical ; but thofe which were 
negative with them, I found to be negative with thefe 
alfo A A In all the experiments with the flannel, I had 
hitherto 
(h) All thefe fubft’ances have fmooth furfaces. 
(i) On this' 1 account an ingenious friend of mine propofed the following; 
queftion, vi%. Whether, if the elediric matter were inherent (as I aflerted) in: 
the different fubftances I examined, the kind of ele&ricity could be changed by. 
the ufe of different rubbers? I reminded him of Mr. canton’s experiments 
with a glafs tube, and informed him, that a ftick of fealing-wax becomes pofi- 
tively eleftrified by dipping it in quickfilver, or exciting it with a flip of tin- 
foil ; that a fmooth glafs tube may be made negative by drawing it cxofs-wjfe 
over 
