tively long, and by its zigzag form represents lightning im minia- 
If, in the next place, a sufficiently large pane of glass being 
interposed, the disks be made to serve as a coating to the glass, 
the surfaces of the pane which they touch will become oppositely 
charged. If immediately after the charging is effected, both disks 
being insulated, the knuckle of the operator, or any other con- 
ducting bedy in communication with the earth, be approached 
to either disk, a spark will pass, and on contact, a certain portion 
of electricity will be discharged. This is what I would call free 
electricity : but on making a conducting communication between 
the disks acting as coatings, a much larger discharge of electricity 
will take place. This is what I would call neutralized or dissim- 
the square of twelve hundred inversely ; or in other words nearly 
asa million and a half to one. It follows that in the phenom- 
ena of discharges from a prime conductor the neutralizing or dis- 
simulating influence of the conducting superficies opposed to it 
must be too small to be regarded. . 
The allegation of Faraday, that no mode has been discovered 
by which to place the particles of a conductor in relation to one 
electricity, and not at the same time to the other, 1s verified, as 
r. Goodman has observed, when the friction between the rub- 
ber and glass takes place. The glass becomes positive to pre- 
cisely the same extent as the rubber becomes negative ; but when 
the vitreous surface thus excited moves away from the ru ber, 
the compensating electricity of the rubber being no longer at 
hand, that upon the glass cannot realize Faraday’s idea, except- 
Ing so far as it may be competent to act upon the walls, ceiling, 
and floor of the apartment, as electricity on the inner surface of a 
yden jar acts upon the outer surface. But in the case in point, 
the electric interposed is so enormously thick, compared with the 
