384 
The Source of Electric Energy . 
[July, 
of light. And if the wire be led to earth, the electricity 
will disperse as completely as the light would in the former 
case. 
There are electrical phenomena which we cannot discover 
in light, and light phenomena which we cannot discover in 
electricity. But they each exist under conditions in which 
it is impossible to place the other. In short, as under the 
form of light we are enabled to discover many of the pheno- 
mena of radiant energy and of its relations to substance, so 
under the form of electricity we are enabled to discover 
others of these phenomena. To gain a full conception of 
radiant energy, the phenomena of etherial radiance and 
electricity must be considered in common, and dealt with as 
the various phases of one general mode of motion. 
The most marked of these peculiar electrical phenomena 
are those of induction. Whether or not light rays have any 
analogous characters it is impossible to decide experi- 
mentally, since light cannot be placed under the conditions 
necessary to induction. We cannot charge a transparent 
with light, and examine its behaviour under such conditions, 
as we can charge a conductor with electricity and examine 
its behaviour. In the investigation of radiant phenomena, 
then, electricity affords us peculiar facilities in one portion 
of the field, as light and radiant heat affords us peculiar 
facilities in another portion of the field. 
And in connection with eleCtric induction, there is another 
special feature of eleCtric energy which is full of significance. 
This is the faCt of its existence in two opposite and mutually 
repressive states, its positive and negative conditions. By 
induction, we simply mean a separation of the energy of 
molecules into these two eleCtric states. It is produced 
under the influence of eleCtric energy in some conductor, 
and consists in a disturbance of the molecular energies in 
neighbouring matter, and a separation of these energies into 
two opposite states, known as the positive and negative 
eleCtric states. And this separation is accompanied by what 
seems a repulsion of the eleCtric state resembling that in the 
charged conductor, and an attraction of the opposite state of 
eleCtric energy. This influence extends in all directions, 
internally as well as externally. To it is due the confine- 
ment of electricity to the surface of the conductor, as will 
be shown further on. 
The influence of inductive energy appears to be almost or 
quite as universal as that of gravity. It extends indefi- 
nitely outward from the electrically excited body, and affeCts 
all materials, of whatever character, though not with equal 
