In recording my investigations on the subject of radiant matter and
the state of gaseous residues in high vacua under electrical strain, I
must refer to certain attacks on the views I have propounded. The most
important of these questionings are contained in a volume of "Physical
Memoirs," selected and translated from foreign sources under the
direction of the Physical Society (vol. i., part 2). This volume
contains two memoirs, one by Hittorff on the "Conduction of
Electricity in Gases," and the other by Puluj on "Radiant Electrode
Matter and the So-called Fourth State." Dr. Puluj's paper concerns me
most, as the author has set himself vigorously to the task of opposing
my conclusions. Apart from my desire to keep controversial matter out
of an address of this sort, time would not permit me to discuss the
points raised by my critic; I will, therefore, only observe in passing
that Dr. Puluj has no authority for linking my theory of a fourth
state of matter with the highly transcendental doctrine of four
dimensional space.
Reference has already been made to the mistaken supposition that I
have pronounced the thickness of the dark space in a highly exhausted
tube through which an induction spark is passed to be identical with
the natural mean free path of the molecules of gas at that exhaustion.
I could quote numerous passages from my writings to show that what I
meant and said was the mean free path as amplified and modified by the
electrification.[2] In this view I am supported by Prof. Schuster,[3]
who, in a passage quoted below, distinctly admits that the mean free
path of an electrified molecule may differ from that of one in its
ordinary state.
[Footnote 2: "The thickness of the dark space surrounding the negative
pole is the measure of the mean length of the path of the gaseous
molecules between successive collisions. The electrified molecules are
projected from the negative pole with enormous velocity, varying,
however, with the degree 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." 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
material of the poles.
Puluj declares that the phenomena I have described in high vacua are
produced by his irregularly shaped lumps of radiant electrode matter.
My contention is that they are produced by radiant matter of the
residual molecules of gas.
Were it not that in this case we can turn to experimental evidence, I
would not mention the subject to you. On such an occasion as this
controversial matter must have no place; therefore I content myself at
present by showing a few novel experiments which demonstratively prove
my case.
Let me first deal with the radiant electrode hypothesis. Some metals,
it is well known, such as silver, gold or platinum, when used for the
negative electrode in a vacuum tube, volatilize more or less rapidly,
coating any object in their neighborhood with a very even film. On
this depends the well known method of electrically preparing small
mirrors, etc. Aluminum, however, seems exempt from this volatility.
Hence, and for other reasons, it is generally used for electrodes.
If, then, the phenomena in a high vacuum are due to the "electrode
matter," the more volatile the metal used, the greater should be the
effect.[6]
[Footnote 6: In a valuable paper read before the Royal Society,
November 20, 1890, by Professors Liveing and Dewar, on finely divided
metallic dust thrown off the surface of various electrodes, in vacuum
tubes, they find not only that dust, however fine, suspended in a gas
will not act like gaseous matter in becoming luminous with its
characteristic spectrum in an electric discharge, but that it is
driven with extraordinary rapidity out of the course of the
discharge.]
Here is a tube (Fig. 15, P=0.00068 millimeter, or 0.9 M), with two
negative electrodes, AA', so placed as to protect two luminous spots
on the phosphorescent glass of the tube. One electrode, A', is of pure
silver, a volatile metal; the other, A, is of aluminum, practically
non-volatile. A quantity of "electrode matter" will be shot off from
the silver pole, and practically none from the aluminum pole; but you
see that in each case the phosphorescence, CC', is identical. Had the
radiant electrode matter been the active agent, the more intense
phosphorescence would proceed from the more volatile pole.
A drawing of another experimental piece of apparatus is shown in Fig.
16. A pear-shaped bulb of German glass has near the small end an inner
concave negative pole, A, of pure silver, so mounted that its
inverted image is thrown upon the opposite end of the tube. In front
of this pole is a screen of mica, C, having a small hole in the
center, so that only a narrow pencil of rays from the silver pole can
pass through, forming a bright spot, D, at the far end of the bulb.
The exhaustion is about the same as in the previous tube, and the
current has been allowed to pass continuously for many hours so as to
drive off a certain portion of the silver electrode; and upon
examination it is found that the silver has all been deposited in the
immediate neighborhood of the pole; while the spot, D, at the far end
of the tube, that has been continuously glowing with phosphorescent
light, is practically free from silver.
[Illustration: FIG. 15.--PRESSURE = 0.00068 MM. = 0.9 M.]
The experiment is too lengthy for me to repeat it here, so I shall not
attempt it; but I have on the table the results for examination.
The identity of action of silver and aluminum in the first case, and
the non-projection of silver in this second instance, are in
themselves sufficient to condemn Dr. Puluj's hypotheses, since they
prove that phosphorescence is independent of the material of the
negative electrode. In front of me is a set of tubes that to my mind
puts the matter wholly beyond doubt. The tubes contain no inside
electrodes with the residual gaseous molecules; and with them I will
proceed to give some of the most striking radiant-matter experiments
without any inner metallic poles at all.
[Illustration: FIG. 16.--PRESSURE = 0.00068 MM. = 0.9 M.]
In all these tubes the electrodes, which are of silver, are on the
outside, the current acting through the body of the glass. The first
tube contains gas only slightly rarefied and at the stratification
stage. It is simply a closed glass cylinder, with a coat of silver
deposited outside at each end, and exhausted to a pressure of 2
millimeters. The outline of the tube is shown in Fig. 17. I pass a
current, and, as you see, the stratifications, though faint, are
perfectly formed.
[Illustration: FIG. 17.--PRESSURE = 2 MM.]
The next tube, seen in outline in Fig. 18, shows the dark space. Like
the first it is a closed cylinder of glass, with a central indentation
forming a kind of hanging pocket and almost dividing the tube into two
compartments. This pocket, silvered on the air side, forms a hollow
glass diaphragm that can be connected electrically from the outside,
forming the negative pole, A; the two ends of the tube, also outwardly
silvered, form the positive poles, B B. I pass the current, and you
will see the dark space distinctly visible. The pressure here is 0.076
millimeter, or 100 M. The next stage, dealing with more rarefied
matter, is that of phosphorescence. Here is an egg-shaped bulb, shown
in Fig 19, containing some pure yttria and a few rough rubies. The
positive electrode, B, is on the bottom of the tube under the
phosphorescent material; the negative, A, is on the upper part of the
tube. See how well the rubies and yttria phosphorescence shows under
molecular bombardment, at an internal pressure of 0.00068 millimeter,
or 0.9 M.
[Illustration: FIG. 18.--PRESSURE = 0.076 MM. = 100 M.]
A shadow of an object inside a bulb can also be projected on to the
opposite wall of the bulb by means of an outside pole. A mica cross is
supported in the middle of the bulb (Fig. 20), and on connecting a
small silvered patch, A, on one side of the bulb with the negative
pole of the induction coil, and putting the positive pole to another
patch of silver, B, at the top, the opposite side of the bulb glows
with a phosphorescent light, on which the black shadow of the cross
seems sharply cut out. Here the internal pressure is 0.00068
millimeter, or 0.9 M.
[Illustration: FIG. 19.--PRESSURE = 0.00068 MM. = 0.9 M.]
[Illustration: FIG. 20.--PRESSURE = 0.00068 MM. = 0.9 M.]
[Illustration: FIG. 21.--PRESSURE = 0.001 MM. = 1.3 M.]
Passing to the next phenomenon, I proceed to show the production of
mechanical energy in a tube without internal poles. It is shown in
Fig. 21 (P = 0.001 millimeter, or 1.3 M). It contains a light wheel of
aluminum, carrying vanes of transparent mica, the poles, A B, being in
such a position outside that the molecular focus falls upon the vanes
on one side only. The bulb is placed in the lantern and the image is
projected on the screen; if I now pass the current, you see the wheels
rotate rapidly, reversing in direction as I reverse the current.
Here is an apparatus (Fig. 22) which shows that the residual gaseous
molecules when brought to a focus produce heat. It consists of a glass
tube with a bulb blown at one end and a small bundle of carbon wool,
C, fixed in the center, and exhausted to a pressure of 0.000076
millimeter, or 0.1 M. The negative electrode, A, is formed by coating
part of the outside of the bulb with silver, and it is in such a
position that the focus of rays falls upon the carbon wool. The
positive electrode, B, is an outer coating at the other end of the
tube. I pass the current, and those who are close may see the bright
sparks of carbon raised to incandescence by the impact of the
molecular stream.
You thus have seen that all the old "radiant matter" effects can be
produced in tubes containing no metallic electrodes to volatilize. It
may be suggested that the sides of the tube in contact with the
outside poles become electrodes in this case, and that particles of
the glass itself may be torn off and projected across, and so produce
the effects. This is a strong argument, which fortunately can be
tested by experiment. In the case of this tube (Fig. 23, P = 0.00068
millimeter, or 0.9 M), the bulb is made of lead glass phosphorescing
blue under molecular bombardment. Inside the bulb, completely covering
the part that would form the negative pole, A, I have placed a
substantial coat of yttria, so as to interpose a layer of this earth
between the glass and the inside of the tube. The negative and
positive poles are silver disks on the outside of the bulb, A being
the negative and B the positive poles. If, therefore, particles are
torn off and projected across the tube to cause phosphorescence, these
particles will not be particles of glass, but of yttria; and the spot
of phosphorescent light, C, on the opposite side of the bulb will not
be the dull blue of lead glass, but the golden yellow of yttria. You
see there is no such indication; the glass phosphoresces with its
usual blue glow, and there is no evidence that a single particle of
yttria is striking it.
[Illustration: Fig. 22.--Pressure = 0.000076 MM. = 0.1 M.]
[Illustration: Fig. 23.--Pressure = 0.00068 MM. = 0.9 M.]
Witnessing these effects I think you will agree I am justified in
adhering to my original theory, that the phenomena are caused by the
radiant matter of the residual gaseous molecules, and certainly not by
the torn-off particles of the negative electrode.