Obfervations on a uezd Electrical Machine . 5 1 $ 
indication that the point had received electricity, and, as 
before obferved, that the coated board, being feparated 
from the wax, &c. was ftrongly electrified plus ; and confe- 
quently, the coating of wax, 8cc, on the plate of glafs, 
minus . Thefe phenomena, being fo often produced, 
without a frefli excitation of the wax, though they are 
aftoni filing to ftrangers, will not be fo furprizing to elec- 
tricians, who have conlidered Mr. grey’s experiment 
with a cone of fulphur, contained in a glafs veffel, which, 
as often as they were feparated, fliewed ligns of electri- 
city in all hates of the weather. See Dr. priestlev’s 
Hiftory of Electricity, ad edit. p. 39. I have fliewn at 
large, in a former paper, that merely hearing either glafs 
or amber will not make them electrical ; but the friction 
of glafs againft glafs, or fealing-wax againft fcaling-wax, 
previoully warmed, I find, will excite either of thefe fub- 
ftances; and my ingenious and learned friend thomas 
ronayne, Efq. informs me, that he had long fince made 
the fame remark on fealing-wax. But, prefling a finger 
in the gentlefi manner on the amber, alter heating, will 
excite it. Indeed, a fine piece, which I frequently carry 
in my pocket, I always perceive to be electrical, without 
any other friction than what it receives from the pocket. 
Sealing-wax, Mr. ronayne tells me, he always found to 
be affeCted in the fame manner; and negative electrics, 
per fe, being once thoroughly excited, are obferved to re- 
tain their electrical quality very long, as they do not fo 
•foon attraCt the moiiture in the atmofphere as glafs. 
Glafs, however, will retain its electricity many hours, as 
I have had frequent occafion to remark. My late friend 
Vo l. LX VI. Yy .y Mr. 
