[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." I say "misleading," for while both his and my definitions
equally admit the existence of "Radiant Matter," he drags in the
hypothesis that the radiant matter is actually the disintegrated