egative, is composed of elementary
parts which behave like atoms of electricity."

The second law seems, in fact, analogous to the law of multiple
proportions in chemistry, and it shows us that the quantities of
electricity carried vary from the simple to the double or treble,
according as it is a question of a uni-, bi-, or trivalent metal; and
as the chemical law leads up to the conception of the material atom,
so does the electrolytic law suggest the idea of an electric atom.

CHAPTER VI

THE ETHER

Sec. 1. THE LUMINIFEROUS ETHER

It is in the works of Descartes that we find the first idea of
attributing those physical phenomena which the properties of matter
fail to explain to some subtle matter which is the receptacle of the
energy of the universe.

In our times this idea has had extraordinary luck. After having been
eclipsed for two hundred years by the success of the immortal
synthesis of Newton, it gained an entirely new splendour with Fresnel
and his followers. Thanks to their admirable discoveries, the first
stage seemed accomplished, the laws of optics were represented by a
single hypothesis, marvellously fitted to allow us to anticipate
unknown phenomena, and all these anticipations were subsequently fully
verified by experiment. But the researches of Faraday, Maxwell, and
Hertz authorized still greater ambitions; and it really seemed that
this medium, to which it was agreed to give the ancient name of ether,
and which had already explained light and radiant heat, would also be
sufficient to explain electricity. Thus the hope began to take form
that we might succeed in demonstrating the unity of all physical
forces. It was thought that the knowledge of the laws relating to the
inmost movements of this ether might give us the key to all phenomena,
and might make us acquainted with the method in which energy is stored
up, transmitted, and parcelled out in its external manifestations.

We cannot study here all the problems which are connected with the
physics of the ether. To do this a complete treatise on optics would
have to be written and a very lengthy one on electricity. I shall
simply endeavour to show rapidly how in the last few years the ideas
relative to the constitution of this ether have evolved, and we shall
see if it be possible without self-delusion to imagine that a single
medium can really allow us to group all the known facts in one
comprehensive arrangement.

As constructed