e cathode particle therefore
goes about three thousand times faster than the earth in its orbit.
The relation is also invariable, even when the substance of which the
cathode is formed is changed or one gas is substituted for another. It
is, on the average, a thousand times greater than the corresponding
relation in electrolysis. As experiment has shown, in all the
circumstances where it has been possible to effect measurements, the
equality of the charges carried by all corpuscules, ions, atoms, etc.,
we ought to consider that the charge of the electron is here, again,
that of a univalent ion in electrolysis, and therefore that its mass
is only a small fraction of that of the atom of hydrogen, viz., of the
order of about a thousandth part. This is the same result as that to
which we were led by the study of flames.

The thorough examination of the cathode radiation, then, confirms us
in the idea that every material atom can be dissociated and will yield
an electron much smaller than itself--and always identical whatever
the matter whence it comes,--the rest of the atom remaining charged
with a positive quantity equal and contrary to that borne by the
electron. In the present case these positive ions are no doubt those
that we again meet with in the canal rays. Professor Wien has shown
that their mass is really, in fact, of the order of the mass of atoms.
Although they are all formed of identical electrons, there may be
various cathode rays, because the velocity is not exactly the same for
all electrons. Thus is explained the fact that we can separate them
and that we can produce a sort of spectrum by the action of the
magnet, or, again, as M. Deslandres has shown in a very interesting
experiment, by that of an electrostatic field. This also probably
explains the phenomena studied by M. Villard, and previously pointed
out.

Sec. 2. RADIOACTIVE SUBSTANCES

Even in ordinary conditions, certain substances called radioactive
emit, quite outside any particular reaction, radiations complex
indeed, but which pass through fairly thin layers of minerals, impress
photographic plates, excite fluorescence, and ionize gases. In these
radiations we again find electrons which thus escape spontaneously
from radioactive bodies.

It is not necessary to give here a history of the discovery of radium,
for every one knows the admirable researches of M. and Madame Curie.
But subsequent to these first studies, a great number of facts h