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fire : eledtrify the apparatus to a confiderable degree ; 
then touch the tin tube with a finger, or any other 
condudtor, and the balls will, notwithftanding, con- 
tinue to repel each other ; tho’ not at fo great a di- 
fiance as before. 
The air furrounding the apparatus to the difiance 
of two or three feet, is fuppofed to contain more or 
lefs of the eledtrical fire, than its common Share, as 
the tin tube is electrified pofitively, or negatively ; and 
when very dry, may not part with its overplus, or 
have its deficiency Supplied fo fuddenly, as the tin ; 
but may continue to be eledtrified, after that has been 
touch’d, for a considerable time. 
Experi?nent 8. 
Having made the Torricellian vacuum about five 
feet long, after the manner defcribed in the Philofo- 
phical TranfaStions , Vol. xlvii. p. 370. if the ex- 
cited tube be brought within a Small diftance of it, 
a light will be Seen thro’ more . than half its length : 
which foon vanishes, if the tube be not brought 
nearer; but will appear again, as that is moved far- 
ther off. - This may be repeated feveral times, with- 
out exciting the tube afrefh. 
This experiment may be confider’d as a kind of 
ocular demonstration of the truth of Mr. Franklin’s 
hypothefis ; that when the eledtrical fluid is con- 
denfed on one fide of thin glafs, it will be repel- 
led from the other, if it meets with no refiflance. 
According to which, at the approach of the excited 
tube, the fire is fuppofed to be repelled from the 
infide of the glafs Surrounding the vacuum, and to 
Y y 2 be 
