of exhaustion and intensity of the induction
current."--_Phil. Trans._, part i., 1879, par. 530.

"The extra velocity with which the molecules rebound from the excited
negative pole keeps back the more slowly moving molecules which are
advancing toward the pole. The conflict occurs at the boundary of the
dark space, where the luminous margin bears witness to the energy of
the discharge."--_Phil. Trans._, part i., 1879, par. 507.

"Here, then, we see the induction spark actually illuminating the
lines of molecular pressure caused by the excitement of the negative
pole."--_R.I. Lecture_, Friday, April 4, 1879.

"The electrically excited negative pole supplies the _force majeure_,
which entirely, or partially, changes into a rectilinear action the
irregular vibration in all directions."--_Proc. Roy. Soc._, 1880. page
472.

"It is also probable that the absolute velocity of the molecules
is increased so as to make the mean velocity with which they
leave the negative pole greater than that of ordinary gaseous
molecules."--_Phil. Trans._, part ii., 1881, par. 719.]

[Footnote 3: "It has been suggested that the extent of the dark space
represents the mean free path of the molecules.... It has been pointed
out by others that the extent of the dark space is really considerably
greater than the mean free path of the molecules, calculated according
to the ordinary way. My measurements make it nearly twenty times as
great. This, however, is not in itself a fatal objection; for, as we
have seen, the mean free path of an ion may be different from that of
a molecule moving among others."--Schuster, _Proc. Roy. Soc_., xlvii.,
pp. 556-7.]

The great difference between Puluj and me lies in his statement
that[4] "the matter which fills the dark space consists of mechanical
detached particles of the electrodes which are charged with statically
negative electricity, and move progressively in a straight direction."

[Footnote 4: "Physical Memoirs," part ii., vol. i., p. 244. The
paragraph is italicized in the original.]

To these mechanically detached particles of the electrodes, "of
different sizes, often large lumps,"[5] Puluj attributes all the
phenomena of heat, force and phosphorescence that I from time to time
have described in my several papers.

[Footnote 5: _Loc. cit._, p. 242.]

Puluj objects energetically to my definition "Radiant Matter," and
then proposes in its stead the misleading term "Radiant Electrode
Matter."