ar ar 
48 Dr. Hare on the Theories of Electrical Phenomena. 
slightest statical excitement; yet neither is in the most minute 
degree affected by the polarization which affects the other. — 
64. The charge which may exist in a coated pane affords an- 
other exemplification of statical or electro-ethereal polarity. In 
this case, according to Faraday, the particles of glass are thrown 
into a state of electro-polarity, and are, in fact, partially affected 
as if they belonged to a conductor; so that insulators and con- 
ductors differ only in the possession ‘ina high degree by the one, 
of a susceptibility of which the other is possessed to an extent 
barely perceptible. The facts seem to me only to show, that 
either an insulator or conductor may be both affected by the 
same polarizing force, the transmission of which the one facili- 
tates, the other prevents. Iam under the impression that it is 
only by the diruptive process that mpeg ad passes through glass ; 
of course involving a fracture. It gets through a pane or jar, not 
y aid of the vitreous particles, but in despite of their opposing 
coherence. The glass in such cases is not liable to be fused, de- 
flagrated, or dissipated, as‘conductors are. It is forced out of the 
way of the electrical waves, being incapable of becoming a party 
to them. Discharges will take place through a vacuity, rather 
than through the thinnest leaf of mica. But if, as Faraday has 
alleged, from within a glass flask hermetically sealed, an electri- 
cal charge has been found to escape, after a long time, it pro 
only that glass is not a perfect insulator, not that perfect insula- 
tion and perfect conduction are different extremes of the same 
property. On the contrary, the one is founded upon a constitu- 
tion competent to the propagation within it of the electro-polar- 
izing waves, with miraculous facility, while the other is founded 
either on an absolute incapacity, or comparatively an et 
small ability to be the medium of their conveyance. The on 
extremely retards, the other Soemerely expedites its resell 
through a space otherwise void.* 
Competency of a Wire to convey a Galvanic Discharge is as its 
sectional area, while statical discharges of frictional electricity 
preferring the surface are promoted. by its extension. Yet in 
proportion as such discharges are heavy, the ability of a wire 
to convey them and its magnetic energy become more depend- 
ent on its sectional area and less upon extent of surface. 
65. Reference has been made to two modes of electrical con- 
duction, in one of which the efficacy is as the surface; in t 
other, as the area of a section of the conductor. Although glass 
be substantially a non-conductor, the power of the su urface of 
ass when moistened, or gilt, to discharge statical electricity, 
* By a void, I mean a Torricellian vacuum. The 6 omni resence of the —— 
ether must render the existence of a perfect void fs i 
