364 On Electricity. 
Symmer’s arrangement, by including a single leaf of paper 
between two tinfoil slips in the middle of a book; it has 
sometimes happened that the perforation of the paper took 
place in a right line, and insuch cases both slips of tinfoit 
have been indented in one direction only, and inyariably in a 
direction from the positive to the negative surface. 
From these facts, (and from various others, which if my 
leisure permitted T could state,) [feel authorised to con- 
clude that Mr. Symmer mistook the expansive effects of 
electricity for an evidence of its direction; and that Mr. E. 
Walker has ingeniously amplified this error by adducing 
in his second experiment two opposite impressions, which 
are produced owt of the electrical circuit, as an evidence of 
opposite currents supposed to take place within it. 
With respect to the permanence of the effects produced 
by electrical influence, Mr. W. has fallen into error by 
confounding them with communicated electricity. If, after 
bringing an electrified body near an insulated conductor, 
on withdrawing it the insulated conductor remains per- 
manently electrified, it must have dost or received electricity ; 
and in either case it is electrified by communication and not 
Ly position, whether its loss or gain be the consequence of 
the contact of some conducting body, or the imperfection 
of its own insulation during the disturbance of its natural 
electricity ; and one of these causes must operate to produce 
permanent electricity in such an experiment: for neilher an 
insulated rod nor a gold-leaf electrometer, if properly con- 
structed, will be permanently electrified by approximation 
to an electrified body; unless they communicate by imper- 
Sect insulation, or pointed terminations with surrounding 
unelectrified substances during such approximation. These 
are facts, which the constant repetition of such experiments 
professionally enables me to state with confidence; and 
they are indeed such as amongst electricians are generally 
admitted: but perhaps Mr. Walker has yet to learn, that a 
conducting body supported by dry glass, and surrounded 
by dry air, may be still very far from perfectly insulated. 
London G f 
Qct, 12, 1813. ‘ de SIN GERo 
XLV, dn 
