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LXXIX. Farther Experiments in Electricity ; 
hy Mr. Benjamin Wilfon, F. R. S. 
To the Right Honourable the Earl of Macclesfield, 
Prefident of the Royal Society. 
My Lord, 
Read Nov. 13, ‘'|"N my letter upon the Tourmalin, which 
i 7 6o. j t h e } lonour of communicating 
to the Royal Society in December laft, there are fome 
experiments to {hew, that glafs is permeable by elec- 
tricity. I have fince made others of the like kind, 
which feem to favour the fame opinion. 
The high regard your Lordfliip has always fhewn 
for experimental philofophy, encourages me to lay 
before you thefe experiments, with a few others, 
of a very curious nature. 
But I beg leave, firft, to take notice, that our 
ele&rical apparatus is much improved, by the dis- 
covery of Father Windelinus Ammerfm , of Switzer- 
land , who, in a Latin treatife published in 17^4, has 
fhewn us, that wood , properly dried, till it becomes 
very brown, is a non-condu£tor of electricity * j and 
recommends boiling the wood in linfeed oil, or 
covering it all over with varnifh, after being dried, 
to prevent any return of moifture into its pores. He 
* It appears, from the Philofophical Franfadlions, fo early as 
the year 1747, that Dr. IVatfon having occafion to fupport a long 
wire, in the experiment made near Shooter’s Hill, with a view to 
determine the velocity of the electric fluid, ufed flakes of dry wood, 
(which, he tells me, were baked ) to prevent the eledric fluid from 
efcaping into the ground. 
adds, 
