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LXXI. A Letter from John Canton, M. A. 
and F. R . S. to Benjamin Franklin, 
LL. D. and F. R. S. containing fo7ne Re- 
marks on Mr. Delaval s FleElrical Experi- 
ments. 
Dear Sir, 
Read Feb. 4, Tk yfR. Delaval, in his curious eleCtrical 
1762. |Y| experiments, found that Portland 
ftone, common tobacco-pipe, &c. would readily con- 
duct the electrical fluid, when very hot, or when quite 
cold j but were non-conduCtors in an intermediate 
ftate. As no one, that I know of, has yet attempted 
to account for this, I (hall fubmit the following fo- 
lution to your judgment.. 
The ftone, tobacco-pipe, wood, &c. I apprehend, 
conduct when cold, by the moifture they contain in 
that ftate; when their moifture is evaporated by heat, 
they become non-conduCtors ; and when they are 
made very hot, the hot air at, or near their furfaces, 
will conduCt, and the bodies appear to be conductors 
again. 
To prove that hot air will conduCt the eleCtrical 
fluid, let the end of a poker, when red-hot, be 
brought, but for a moment, within three or four 
inches of a fmall eleCtrified body, and its eleCtrical 
power will be almoft, if not entirely deftroyed. 
And if excited amber, &c. be held within an 
inch of the flame of a candle, it will lofe its elec- 
Nnn 2 tricity 
