An Attempt Towards a Chemical Conception of the Ether

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*4

A CHEMICAL CONCEPTION
OF THE ETHER

BY THE SAME AUTHOR

THE PRINCIPLES OF CHEMISTRY

Translated from the Russian (Sixth Edition)

By GEORGE KAMENSKY, A.R.S.M.
qf the Imperial Mint, St. PtUr iburg

AND

Edited by T. A. LAWSON, B.Sc., PhJ).
With 96 Illustrations. 2 vols. 8yo. 86s.

LONGMANS, GBBEN, 6 00. 89 Paternoster Bow, London
New York and Bombay.

e>

AN ATTEMPT TOWARDS

A CHEMICAL CONCEPTION

OF THE ETHEK

BY

PROFESSOR D. MENDEL^EFF

TRANSLATED FROM THE RUSSIAN

BY

GEORGE KAMENSKY, A.R.8.M.

OF THE IMPERIAL HINT. ST. PETEBBBUBO

LONGMANS, GREEN, AND CO.

89 PATEBNOBTEB BOW, LONDON
NEW TOBK AND BOMBAY

1904

All rights referred

/ ^2* 3fO, &

-0 '

'W.

\

N

s.

/

CHEMICAL CONCEPTION OF THE ETHER

In his ' Dictionnaire Complet,' P. Larousse
defines the ether as 'an imponderable elastic
fluid, filling space and forming the source of
light, heat, electricity, etc.' This is laconic, but
sufficient to raise some misgivings in the mind
of a thoughtful man of science. He is obliged
to admit, in the ether, the properties of a sub-
stance (fluid), while at the same time, in order to
explain in some way the transmission of energy
through space by its motion, the ether is assumed
to be an all-pervading « medium.' Moreover, in
order to explain the phenomena of light, elec-
tricity, and even gravity, this medium is supposed
to undergo various disturbances (perturbations)
and changes in its structure (deformation), like
those observed in solids, liquids, and gases. If
the fluid medium permeates everything and
everywhere, it cannot be said to have weight,

B

2 A CHEMICAL CONCEPTION OF THE ETHER

just as the ponderability of air could not be
recognised before the invention of the air-pump.
Yet the ether must have weight, because, since
the days of Galileo and Newton, the quality
of gravitation or of weight forms a primary
property of substances. From various con-
siderations Lord Kelvin came to the conclusion
that a cubic metre of ether should weigh about
and not less than 0-000,000,000,000,000,1 grm.,
while a cubic metre of the lightest gas, hydrogen,
weighs 90 grams under the atmospheric pressure.
The above-mentioned misgivings of the thought-
ful scientist begin in his most plausible endea-
vours to ascribe a certain weight or mass to the
ether, for the question naturally arises : At what
pressure and temperature will this weight be
proper to ether ? For at infinitely small pressures
or exceedingly high temperatures steam or
hydrogen would have as small a density as that
given by Lord Kelvin for the ether. And as
regards the density of the ether in interplanetary
space, neither steam nor hydrogen would have
a measurable density in these regions, notwith-
standing the extreme cold, for the pressure would
be infinitely small. Theoretically, space may be
supposed to be filled with such rarefied residues
of vapours and gases. And this view even

1

J

A CHEMICAL CONCEPTION OF THE ETHER 3

corresponds with Kant's and Laplace's and other
theories, which strive to explain the unity of
plan in the creation of the heavenly bodies. It
also accounts for the uniformity of the chemical
composition of the entire universe, demonstrated
by the spectroscope, as it gives a means, through
the agency of such ether, of interchange between
the heavenly bodies. One of the objects of an
investigation into the elasticity or compressibility
of gases under low pressure, undertaken by me
in the seventies, was to trace, as far as the then
existing methods of measuring low pressures
permitted, the changes proceeding in gases
fcder low press.™, The disomies from
Boyle's law observed (by me and M. Kirpitch*
nikoff, 1874) for all gases, and subsequently con-
firmed by Ramsay and others (although still
denied by some investigators), indicate a certain
uniformity in the behaviour of all gases and a
tendency in them towards a certain limiting
expansion at low pressures, just as there is a
limit to compression (liquefaction and the critical
state). But determinations of very low pressures
are accompanied by insurmountable difficulties.
It proved practically impossible to measure,
with any degree of accuracy, pressures under
tenths of a millimetre of mercury, and this is far

B 2

4 A CHEMICAL CONCEPTION OF THE ETHER

too large a figure for such rarefied media as are
supposed to exist at an elevation of even 50
kilometres above the sea level. Hence the
conception of the ether as a highly rarefied
atmospheric gas cannot so far be subjected
to experimental investigation and measurement,
which alone can direct the mind in the right
direction and lead to reliable results.

But, beyond this, the conception of the ether
as a limiting state of expansion of vapours and
gases cannot sustain even the most elementary
LysU, fo, ethe, cannot be understood otherw£
than as an all-pervading ubiquitous substance,
and this is not the property of either gases or
vapours. Both the latter are liquefiable under
pressure, and cannot be said to permeate all sub-
stances, although they are widely distributed in
nature, even in meteorites. Moreover — and this
is the most important-they vary infinitely in
their chemical nature and in their relations to
other substances, while the ether, as far as is
known, is invariable. Owing to the variety of
their chemical properties, all vapours and gases
should react differently on the bodies which they
permeate if they were components of the ether.

Before proceeding further, I think it neces-
sary to justify the chemical views here and

A CHEMICAL CONCEPTION OF THE ETHER 5

elsewhere brought into play. In the days of
Galileo and Newton it was possible, although
difficult, to conceive ether apart from them.
But now it would be contrary to the most
fundamental principles of natural science, for
chemistry, since Lavoisier, Dalton, and Avogadro
Gerhardt, has acquired the most sacred rights of
citizenship in the great company of the natural
sciences, and by placing the mass (weight) of a
substance among its paramount conceptions it
has followed the path indicated by Galileo and
Newton. Moreover, chemistry and its methods
alone have promoted in science a desire to
apprehend bodies and their phenomena in their
ultimate relations, through a conception of the
reaction of their infinitely small parts or atoms
which may in fact be regarded as indivisible in-
dividuals, having nothing in common with the
mechanically indivisible atoms of the ancient
metaphysicians. There are many proofs of this ;
it will suffice to mention the fact that the atoms
of modern science have often been explained by
vortex rings, that there was formerly a strong
inclination to conceive the chemical atoms as
built up of themselves, or of a < primary matter,'
and that recently, especially in speaking of the
radio-active substances, a division of chemical

6 A CHEMICAL CONCEPTION OF THE ETHER

atoms into yet smaller ' electrons ' begins to be
recognised ; all of which would be logically im-
possible were the atom regarded as mechanically
indivisible. Chemically the atoms may be
likened to the heavenly bodies, the stars, sun,
planets, satellites, comets, &c. The building up
of molecules from atoms, and of substances from
molecules, is then conceived to resemble the
building up of systems, such as the solar system,
or that of twin stars or constellations, from these
individual bodies. This is not a simple play of
words in modern chemistry, nor a mere analogy,
but a reality which directs the course of all
chemical research, analysis, and synthesis. Che-
mistry has its own microscope for investigating
invisible regions, and being an archi-real science it
deals all the time with its invisible individualities
without considering them mechanically indivisible.
The atoms and molecules which are dealt with
in all provinces of modern mechanics and physics
cannot be other than the atoms and molecules
defined by chemistry, for this is required by the
unity of science. And therefore the meta-
physicians of the present day should, for the
advancement of knowledge, regard atoms in the
same sense as that in which they are understood
by natural science and not after the manner of the

A CHEMICAL CONCEPTION OF THE ETHER 7

ancient metaphysicians of the Chinese or Greek •
schools. If the Newtonian theory of gravity
revealed the existence of forces acting at in-
finitely great distances, the chemistry of Lavoi-
sier, Dalton, and Avogadro Gerhardt, on the
other hand, disclosed the existence of forces
of immense power acting at infinitely small dis-
tances, and transmutable into all other forms of
energy, mechanical and physical. Thus all the
present-day fundamental conceptions of natural
science — and consequently the conception of the
ether — must necessarily be considered under the
combined influence of chemical, physical, and
mechanical teachings. Although sceptical in-
difference is prone to discern only a « working
hypothesis ' in the conception of the ether, yet the
earnest investigator, seeking the reality of truth,
and not the image of fantasy, is forced to ask
himself what is the chemical nature of the ether.
Before endeavouring to give an answer re-
specting the chemical nature of ether, I think it
necessary to state my opinion regarding the
belief held by some in the unity of the substance
of the chemical elements and their origin from
one primary form of matter. According to this
view, ether consists of this primary matter in an
unassociated form, that is, not in the form of the

8 A CHEMICAL CONCEPTION OF THE ETHER

elementary atoms or molecules of substances, but
as the constituent principle out of which the
chemical atoms are formed. This view has
much that is attractive. The atoms are regarded
as proceeding from primary matter in the same
way as celestial bodies are sometimes represented
as being formed from disunited bodies, such as
cosmic dust, etc. The celestial bodies so formed
remain surrounded by the cosmic dust, etc., from
which they took their origin. So also the atoms
remain in the midst of the all-pervading and
primary ether from which they took their origin.
Some persons assume also that atoms can be
split up into their dust or primary matter, just
as comets break up into falling stars ; and that, as
the geological changes of the earth or the build-
ing up and dissociation of heavenly bodies
proceed before our eyes, so also do the atoms
break up and form again in the silence of their
eternal evolution. Others, without denying the
possibility of such a process in exceptional rare
cases, consider the world of atoms to have been
established once for all, and do not admit the
possibility of decomposing the atom into its
primary matter, or of forming new atoms of any
chemical element from this primary matter by
experimental means. In a word, they regard

A CHEMICAL CONCEPTION OF THE ETHER 9

the process of the creation of atoms as finite and
not subject to repetition, while they consider the
ether as the residue remaining after the forma-
tion of atoms. This view need not be considered
here, it being solely the fruit of imagination and
unproved by any experimental investigation.
But the former theory of a progressive evolution
of the substance of atoms cannot be passed un-
noticed by chemistry, for fundamental principles
of this science are the indestructibility of matter
and the immutability of the atoms forming the
elements. If ether were producible from atoms
and atoms could be built up from ether, the
formation of new unlooked-for atoms and the
disappearance of portions of the elements during
experiment would be possible. A belief in such
a possibility has long been held in the minds
of many by force of superstition ; and the more
recent researches of Emmens to convert silver
into gold, and those of Fittica (1900) to prove that
phosphorus can be transformed into arsenic, show
that it yet exists. In the fifty years during
which I have carefully followed the records of
chemistry, I have met with many such instances,
but they have always proved unfounded. It is
not my purpose here to defend the independent
individuality of the chemical elements, but I

10 A CHEMICAL CONCEPTION OF THE ETHER

am forced to refer to it in speaking of the ether,
for it seems to me that, besides being chemically
invalid, it is impossible to conceive of ether as
a primary substance, because such a substance
should have some mass or weight and also
chemical relations — mass in order to explain the
majority of phenomena proceeding at all distances
up to the infinitely great, and chemical relations
in order to explain those proceeding at distances
infinitely small or commensurable with the atoms.
If the question were restricted to the ether which
fills space and serves as a medium for the trans-
mission of energy, it would in a way be possi-
ble to limit oneself to the supposition of mass
without reference to its chemical relations and
even to consider the ether as a primary matter,
just as the mass of a planet may be conceived
without regarding its chemical composition.
But such an indifferent, indefinite ether loses all
sense of reality and awakens the misgivings of the
earnest investigator, directly he realises that it
must permeate all substances. The necessity of
an easy and perfect permeation of all bodies by the
ether has to be admitted, not only for the com-
prehension of many physical phenomena (such
as those of optics), but also owing to the great
elasticity and rarity of the ethereal substance,

A CHEMICAL CONCEPTION OF THE ETHER 11

the atoms of which are always conceived as being
far more minute than the atoms and molecules
of the known chemical substances. Moreover,
this permeability of ether in all bodies explains
why it cannot be isolated from substances, which
indeed behave in respect to ether like a sieve to
water or air. The capacity of the ether to pene-
trate all substances may, however, be regarded as
the ideal of the diffusion of gases through metals
and other diaphragms. Hydrogen, which has a
small atomic weight and is the lightest of all
known gases, not only diffuses more rapidly than
any other gas, but also has the faculty of pene-
trating through walls of such metals as platinum
and palladium, which are impervious to other
gases. This property is certainly due, not only
to the rapidity of the motion of the molecules
of hydrogen, closely connected with its small
density, but also to a chemical faculty of the same
kind as is exhibited in the formation of metallic
hydrides, of solutions, alloys, and other indefinite
compounds. The mechanism of this penetration
may be likened (at the surface of the body pene-
trated) to the solution of a gas in a liquid, that
is, to the gaseous particles leaping into the inter-
stices between the particles of the liquid with a
retardation of their motion (a partial liquefaction

12 A CHEMICAL CONCEPTION OF THE ETHER

of the gas), and a bringing into harmony of the
motion of both kinds of particles. The con-
densed gas absorbed at the surface of contact
travels in all directions through the body, and
diffuses from one layer to another until it
entirely permeates it. The possibility of gaseous
hydrogen acting thus is evident from the fact
that even gold diffuses through solid lead under
the same force. At length, at the opposite
surface of the body penetrated, the condensed
gas will find it possible to escape into greater
freedom, and will continue to pass in this direc-
tion until its degree of concentration becomes the
same on both sides. When this takes place it
does not set up a state of rest, but one of mobile
equilibrium, that is, equal numbers of molecules
or atoms will escape and leap in on the two sides.
If, as it must, ether have the faculty of permeat-
ing all substances, it must be even lighter and
more elastic (greater vis viva) than hydrogen, and,
what is most important, must have a less capacity
than hydrogen to form chemical compounds
with the bodies it permeates. Compounds are
characterised by the fact that the diverse atoms
in them form systems or molecules, in which the
different elements are in compatible, harmonious
motion. We must therefore suppose that such

A CHEMICAL CONCEPTION OF THE ETHER IS

a state of harmonious motion, of, for instance,
hydrogen and palladium, is actually set up in
those atoms of hydrogen which permeate the
palladium, and that in so doing it forms with
the palladium some compound (either Pd,H or
another) which easily dissociates when heated*
Hence it seems to me that the atoms of ether
are so void of this faculty of forming compounds
(which is already weak in hydrogen) that such
compounds dissociate at all temperatures, and
that therefore nothing beyond a certain conden-
sation among the atoms of substances can be
looked for in the ether.

Eight years ago, it would have been most
arbitrary to deny the existence, in the substance
or atoms of ether, of the faculty of forming any
compounds with other chemical elements, for in
those days all the known elements were, directly
or indirectly, capable of entering into mutual
combination. But in 1894 Lord Rayleigh and
Professor Ramsay discovered argon, and defined
it as the most inactive element ; this was followed
by the discovery of helium, the existence of which
Lockyer had predicted by its spectrum as a solar
element, and subsequently by the separation of
neon, krypton, and xenon from air. None of
these five new gases have yet given any definite

14 A CHEMICAL CONCEPTION OF THE ETHER

compounds, although they clearly evince the
faculty of solution, i.e. of forming indefinite,
easily dissociated compounds. Thus we have
now every right to say that the ether is unable to
form any stable compounds with other chemical
atoms, although it permeates all substances.
f Hence the ether may be said to be a ga#, like
helium or argon, incapable of chemical com-
bination. This definition of ether requires further
consideration. The recognition of the ether as
a gas, signifies that it belongs to the category of
the ordinary physical states of matter, gaseous,
liquid, and solid. It does not require the re-
cognition of a peculiar fourth state beyond the
human understanding (Crookes). All mystical,
spiritual ideas about ether disappear. In
calling ether a gas, we understand a ' fluid ' in
the widest sense ; an elastic fluid having no
cohesion between its parts. Furthermore, if
ether be a gas, it has weight ; this is indisputable,
unless the whole essence of natural science, from
the days of Galileo, Newton, and Lavoisier, be
discarded for its sake. But since ether possesses
so great a penetrative power that it passes
through every envelope, it is, of course, im-
possible to experimentally determine its mass in
a given amount of other substances, or the

s

A CHEMICAL CONCEPTION OF THE ETHER 15

weight of a given volume of ether. We ought,
therefore, not to speak of the imponderability of
ether, but only of the impossibility of weighing it.

The, preceding remarks are in exact accord-
ance with the generally accepted conception of
ether. The only addition made is to ascribe
to ether the properties of a gas, like argon and
helium, utterly incapable of entering into true
chemical combination. This point lies at the
basis of our investigation into the chemical
nature of ether, and includes the following two
fundamental propositions : (1) that the ether is
the lightest (in this respect ultimate) gas, and is
endowed with a high penetrating power, which
signifies that its particles have, relatively to other
gases, small weight and extremely high velocity,
and (2) that ether is a simple body (element) in-
capable of entering into combination or reaction
with other elements or compounds, although
capable of penetrating their substance, just as
helium, argon, and their analogues are soluble
in water and other liquids.

The argon group of gases and the periodic
system of the elements have such a close
bearing upon our further consideration of the
chemical nature of ether that it behoves us to
look at them more closely.

16 A CHEMICAL CONCEPTION OF THE ETHER

When in 1869 I first showed the periodic
dependence of the properties of the elements
upon their atomic weights, no element incapa-
ble of forming definite compounds was known,
nor was the existence of such an element even
suspected. Therefore the periodic system was
arranged by me in groups, series, and periods,
starting in group I. and series I., with hydrogen
as the lightest and least dense of all the
elements. It never occurred to me that hydro-
gen might be the starting-point of a system
of elements. Guided by this system, I was
able to predict both the existence of several
unknown elements and also their physical and
chemical properties in a free and combined
state. These elements, gallium, scandium,
and germanium, were subsequently discovered
by Lecoq de Boisbaudran, Nilson, and Winkler
respectively. I made these predictions by
following what is known in mathematics as a
method of interpolation, that is, by finding inter-
mediate points by means of two extreme points
whose relative position is known. The fact of
my predictions having proved true confirmed
the periodic system of the elements, which may
now be considered as an absolute law. So long
as the law remained unconfirmed, it was not

A CHEMICAL CONCEPTION OF THE ETHER 17

possible to extrapolate (i.e. to determine points
beyond the limits of the known) by its means,
but now such a method may be followed, and
I have ventured to do so in the following
remarks on the ether, as an element lighter
than hydrogen. My reason for doing this was
determined by two considerations. In the
first place, I think I have not many years for
delay ; and, in the second place, in recent years
there has been much talk about the division
of atoms into more minute electrons, and it
seems to me that such ideas are not so much
metaphysical as metachemical, proceeding from
the absence of any definite notions upon the
chemism of ether, and it is my desire to replace
such vague ideas by a more real notion of the
chemical nature of the ether. For until some one
demonstrates either the actual transformation
of ordinary matter into ether, or the reverse,
or else the transformation of one element into
another, I consider that any conception of the
division of atoms is contrary to the scientific
teaching of the present day ; and that those
phenomena in which a division of atoms is
recognised would be better understood as a
separation or emission of the generally recognised
and all-permeating ether. In a word, it seems

c

18 A CHEMICAL CONCEPTION OF THE ETHER

to me that the time has arrived to speak of the
chemical nature of ether, all the more so since, so
far as I know, no one has spoken at all definitely
on this subject. When I applied the periodic
law to the analogues of boron, aluminium, and
silicon, I was thirty-three years younger than
now, and I was perfectly confident that sooner
or later my prediction would be fulfilled. Now
I see less clearly and my confidence is not so
great. Then I risked nothing, now I do. This
required some courage, which I acquired when
I saw the phenomena of radio-activity. I then
saw that I must not delay, that perhaps my
imperfect thoughts might lead some one to a
surer path than that which was opened to my
enfeebled vision.

First, I will treat of the position of helium,
argon, and their analogues in the periodic system ;
then of the position of ether in this system ;
and conclude with some remarks on the probable
properties of ether according to the position it
occupies in the periodic system.

When, in 1895, I first heard of argon and its
great chemical inertness, I doubted the ele-
mentary nature of the gas, and thought it might
be a polymeride of nitrogen N 8 , just as ozone,
O s , is a polymeride of oxygen, with the difference

1 •

I

A CHEMICAL CONCEPTION OF THE ETHER 19

that, while ozone is formed from oxygen with the
absorption of heat, argon might be regarded as
nitrogen deprived of heat. In chemistry nitrogen
was always regarded as the type of chemical inert-
ness, i.e. of an element which enters into reaction
with great difficulty, and if its atoms lost heat
in becoming condensed by polymerisation from
N 8 to N 3 , it would form a still less active body ;
just as silica, which is formed from silicon and
oxygen with the evolution of heat, is more inert
than either of them separately. Berthelot sub-
sequently published a similar view on the nature
of argon, but I have now long discarded this and
consider argon to be an independent element, as
Ramsay held it to be from the very beginning.
Many reasons induced me to adopt this view, and
chiefly the facts that (1) the density of argon is
certainly much below 21, namely about 19, that of
H being 1, while the density of N 8 would be about
21, for the molecular weight of N 8 = 14 x 3 = 42
and the density should be half this ; (2) helium,
discovered by Ramsay in 1895, has a density of
about 2 referred to hydrogen, and exhibits the
same chemical inactivity as argon, and in its case
this inactivity can certainly not be due to a
complexity of its molecule ; (8) in their newly
discovered neon, krypton, and xenon, Ramsay and

c 2

^ i

SO A CHEMICAL CONCEPTION OF THE ETHER

Travers found a similar inactivity which, in these
cases also, could not be explained by polymerisa-
tion ; (4) the independent nature of the separate
spectra of these gases, and the invariability of
these spectra under the influence of electric
sparks, proved that they belong to a family of
elementary gases different from all other elements,
and (5) the graduation and definite character of
the physical properties in dependence upon the
density and atomic weight further confirm the
fact of their being simple bodies, whose in-
dividuality, in the absence of chemical reactions,
can only be affirmed from the constancy of their
physical features. An instance of this is seen in
the boiling points (at 760 m.m.) or temperatures
at which the vapour pressures equal the atmo-
spheric pressure and at which the liquid and
gaseous phases are co-existent :

Atomic weight .
Observed density
Observed boiling
point

Helium

Neon

Argon

Krypton

Xenon

4
• 2

19-9
9*95

38
18-8

81-8
40*6

128
63-5

-262°

-239°

-187°

-162°

-100°

This recalls the halogen

group

•
•

—

Fluorine

Chlorine

Bromine

Iodine

Molecular weight .
Vapour density
Boiling point

38

19

-187°

79-9
35-5
-34°

159-9
80

+ 57-7°

254

127

+ 183-7°

A CHEMICAL CONCEPTION OF THE ETHER 21

In both cases the boiling point clearly rises
with the atomic or molecular weight. When
the elementary nature of the argon analogues
and their characteristic chemical inactivity were
once proved, it became essential that they
should take their place in the periodic system of
the elements ; not in any of the known groups
but in a special one of their own, for they
exhibited new, hitherto unknown chemical pro-
perties, and the periodic system embraces in
Srerent groups tLe elements which « —
logous in their fundamental chemical properties,
although not in dependence upon these properties
but upon their atomic weight, which apparently
— previous to the discovery of the periodic law —
stands in no direct relation to these properties.
This was a critical test for the periodic law and
the analogues of argon, but they both stood
the test with perfect success ; that is, the atomic
weights, calculated from the observed densities,
proved to be in perfect accordance with the
periodic law.

Although I assume that the reader is ac-
quainted with the periodic law, yet it may be
well to mention that if the elements be arranged
in the order of their atomic weights it will be
found that similar variations in their' chemical

22 A CHEMICAL CONCEPTION OF THE ETHER

properties repeat themselves periodically, and
that the order of the faculty of the elements to
combine with other elements also corresponds
with the order of their atomic weights. This is
seen in the following simple example.

All the elements having an atomic weight of
not less than 7 and not more than 85*5 fall into
two series :

Li = 70 Be« 91 B»11*0 C-120 N-140 = 16 F-19-0

lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine

Na -23-0 Mg - 243 Al«27*0 Si = 28 4 P-310 S-321 01 = 35*5

Sodium Magnesium Alnminlnm Silicon Phosphorus Sulphur Chlorine

Each pair of elements present a great
similarity in their chief properties ; this is espe-
cially marked in the higher saline oxides, which
in the lower series are :

Na a O, MgO, A1 2 3 , SiO* P 2 6 , SO a , C1 2 7 ,

or

Na t O, Mg 9 0„ A1,C>3, Si,0 4 , P 2 O ft , S 2 0«, a,O r .

Thus the atomic order of the elements exactly
corresponds to the arithmetical order from 1 to 7.
So that the groups of the analogous elements
may be designated by the Roman ciphers I
to VII: and when it is said that phosphorus
* belongs to group V, it signifies that it forms a
higher saline oxide P 2 O s . And if the analogues
of argon do not form any compounds of any
kind, it is evident that they cannot be included

A CHEMICAL CONCEPTION OF THE ETHER 23

in any of the groups of the previously known
elements, but should form a special zero group
which at once expresses the fact of their chemical
indifference. Moreover, their atomic weight
should necessarily be less than those of group
I : Li, Na, K, Rd, and Cs, but greater than
those of the halogens, F, CI, Br, and I, and this
a priori conclusion was subsequently confirmed
by fact, thus :

Halogens Argon analogues Alkali metals

He=4.-0 Ii=7*03

F=19 Ne=19-9 Na=2305

Cl=35-5 Ar=*38 K=391

Br=79*95 Kr=81-8 Rh=85-4

1=127 Xe=128 Cs= 152*9

The five well-known alkali metals correspond
to the newly discovered argon analogues, and the
atomic weights of both exhibit the same common
law of periodicity. But the halogens and alkali
metals are the most chemically active among
the dements, and .re, m „»eover, of opposiS
chemical character, the first being particularly
prone to react with metals and the others with
metalloids, the former appearing at the anode
and the latter at the cathode. They must there-
fore stand at the two extremes of the periodic
system, as in the scheme on page 24.

Although this arrangement best expresses

S* A CHEMICAL CONCEPTION OF THE ETHER

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A CHEMICAL CONCEPTION OF THE ETHER 25

the periodic law, the distribution of the elements
according to groups and series in the table on
page 26 is perhaps clearer.

Here x and y stand for two unknown elements
having atomic weights less than that of hydrogen,
whose discovery I now look for.

A reference to the above remarks on the
argon group of elements shows first of all that
such a zero group as they correspond to could
not possibly have been foreseen under the con-
ditions of chemical knowledge at the time of
the discovery of the periodic law in 1869 ; and,
although I had a vague notion that hydrogen
might be preceded by some elements of less
atomic weights, I dared not put forward such a
proposal, because it was purely conjectural, and I
feared to injure the first impression of the periodic
law by its introduction. Moreover, in those days
the question of the ether did not awaken much
interest, for electrical phenomena were not then
ascribed to its agency, and it is this that now
gives such importance to the ether. But at the
present time, when there can be no doubt that the
hydrogen group is preceded by the zero group
composed of elements of less atomic weights, it
seems to me impossible to deny the existence of
elements lighter than hydrogen.

Let us first consider the element in the first

86 A CHEMICAL CONCEPTION OF THE ETHER

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A CHEMICAL CONCEPTION OF THE ETHER 27

series of the zero group. It is designated by y.
It will evidently exhibit all the fundamental
properties of the argon gases. But first we must
have an approximate idea of its atomic weight.
To do this, let us consider the ratio of the atomic
weights of two elements belonging to the same
group in neighbouring series. Starting with
Ce = 140 and Sn = 119 (here the ratio is 118),
this ratio, in passing to the lower groups and
series, increases constantly and fairly uniformly
as the atomic weights of the elements under
comparison decrease. But we will limit our
calculation to the first and second series, starting
with CI = 35*45 ; for (1) we are exclusively con-
cerned with the lightest elements, (2) the ratio
of the atomic weights is more accurate for these
elements, and (8) the small periods of the typical
elements (which should include the elements
lighter than hydrogen) terminate with chlorine.
As the atomic weight of chlorine is 85*45 and
that of fluorine 19*0, the ratio CI :F = 85*4 : 19-0 =
1*86 ; so also we find :

Group VII

. a : F =1-86

VI

. s : o =2oo

V

. P : N =2-21

IV

. Si :C =2-87

III

. Al : B =2-45

II

. Mg: Be =2-67

I

. Na .* IA =8-28

. Ne : He=4*98

28 A CHEMICAL CONCEPTION OF THE ETHER

This proves that the ratio in the given series

distinctly and progressively increases in passing

from the higher to the lower groups; and,

moreover, that it varies most rapidly between the

first and zero groups. It follows therefore that

the ratio He : y will be considerably greater than

the ratio Li : H which is 6 # 97, so that the ratio

He:y will be at least 10 and probably even

greater. Hence, as the atomic weight He = 4*0,

the atomic weight of y will be not greater thaii

4*0

- - = 0*4 and probably less. Such an analogue

of helium may perhaps be found in coronium,
whose spectrum, clearly visible in the solar
corona above (that is, fiirther from the sun than)
that of hydrogen, is simple like that of helium,
which seems to indicate that it belongs to a gas
resembling helium, which was also predicted
from its spectrum by Lockyer. Young and
Harkness independently observed the spectrum
of this unknown element during the solar eclipse
of 1869. It is characterised by a bright-green line
of wave length 581'7/t/t, while helium is charac-
terised by a yellow line, 587 w* Nasini, Anderlini,
and Salvadori think that they discovered traces
of coronium in their observations on the spectra
of volcanic gases (1898). And as the lines of

A CHEMICAL CONCEPTION OF THE ETHER 29

coronium were also observed, even at distances
many times the radius of the sun above its
atmosphere*" and protuberances, where the hy-
drogen lines are no longer visible, it is evident
that coronium should have a less density and
atomic weight than hydrogen. Moreover, as the
ratio of the specific heats (at a constant pressure
and for a constant volume) of helium, argon,
and their analogues gives reason for thinking
that their molecules (i.e. the amount of matter
occupying, according to Avogadro-Gerhardt's
law, a volume equal to the volume of two parts
by weight of hydrogen) contain only one atom
(like mercury, cadmium, and most metals), it
follows that, if 0*4 be the greatest atomic weight
of the element y, its density referred to hydrogen
should be less than 0*2. Consequently the mole-
cules of this gas will, according to the kinetic
theory of gases, move 2*24 times faster than
those of hydrogen, and if, as Stoney (1894-1898)
and Rostovsky (1899) endeavour to prove, the
progressive motion of the molecules of hydrogen
and helium be such that they can leap out of the
sphere of the earth's attraction, then a gas whose
density is at least five times less than that of
hydrogen could certainly only exist in the atmo-
sphere of a body having as great a mass as the sun.

30 A CHEMICAL CONCEPTION OF THE ETHER

However, this y — coronium or some other
gas with a density about 02— cannot possibly
be ether, its density being too great. It
wanders, perhaps for ages, in the regions of
space, breaks from the shackles of the earth and
again comes within its sphere, but still it cannot
escape from the regions of the sun's attraction,
and there are many heavenly bodies of greater
mass than the sun. But the atoms of ether
must be of another kind ; they must be capable
of overcoming even the sun's attraction, of freely
permeating all space, and of penetrating every-
thing and everywhere. The element y, however,
is necessary for us to be able to mentally realise
the lightest and therefore swiftest element <r,
which I consider may be looked upon as the ether.

We have seen that, besides the ordinary
groups of the chemically active elements, a zero
group of chemically inactive elements must now
be recognised for helium, argon, and their ana-
logues. Thanks to Ramsay's exemplary re-
searches, these elements are now tangible realities,
authentic gases foreign to chemical association,
that is, distinguished by their specific property of
not being chemically attracted to each other or
to other atoms even at infinitely small distances,
and yet having weight, that is, subject to the

A CHEMICAL CONCEPTION OF THE ETHER 31

laws of attraction of mechanics, which has
nothing in common with chemical attraction.
There is some hope that gravity may in some
way or another be explained by means of pres-
sure or impact acting from all sides, but chemical
attraction, which only acts at infinitely small
distances, will long remain an incomprehensible
problem. The problem of the ether is more or less
closely connected with that of gravity, and gains
in simplicity when all question of the chemical
attraction of the atoms of ether is excluded, and
this is accomplished by placing it in the zero
group. But if the series of the elements begins
with series I containing hydrogen, the zero
group has no place for an element lighter than
y 9 like ether. I therefore add a zero series,
besides a zero group, to the periodic system, and
place the element x in this zero series, regarding
it (1) as the lightest of all the elements both in
density and atomic weight ; (2) as the most
mobile gas ; (8) as the element least prone to
enter into combination with other atoms, and
(4) as an all-permeating and penetrating sub-
stance. Of course, this is a hypothesis, but it is
not one constructed for purely ' working ' ends,
but simply from a desire to extend the real
periodic system of the known elements to the

1

32 A CHEMICAL CONCEPTION OF THE ETHER

confines or limits of the lowest dimensions of
atoms, which I cannot and will not regard in
the light of a simple nullity called mass.

Being unable to conceive the formation of
the known elements from hydrogen, I can neither

<r, although it is the lightest of all the elements.
I cannot admit this, not only because no fact
points to the possibility of the transformation of
one element into another, but chiefly because I
do not see that such an admission would in any
way facilitate or simplify our understanding of
the substances and phenomena of nature. And
when I am told that the doctrine of unity in the
material of which the elements are built up
responds to an aspiration for unity in all things,
I can only reply that at the root of all things a
distinction must be made between matter, force,
and mind ; that it is simpler to admit the germs
of individuality in the material elements than
elsewhere, and that no general relation is possible
between things unless they have some individual
character resident in them. In a word, I see no
object in following the doctrine of the unity of
matter, while I clearly see the necessity of re-
cognising the unity of the substance of the ether
and of realising a conception of it, as the utter-

A CHEMICAL CONCEPTION OF THE ETHER 38

most limit of that process by which all the other
atoms of the elements were formed and by
which all substances were formed from these
atoms. To me this kind of unity is far more
real than any conception of the formation
of the elements from a single primary matter.
Neither gravity nor any of the problems of
energy can be rightly understood without a real
conception of the ether as a universal medium
transmitting energy at a distance. Moreover,
a real conception of ether cannot be obtained
without recognising its chemical nature as an
elementary substance, and in these days no
elementary substance is conceivable which is not
subject to the periodic law.

I will therefore, in conclusion, endeavour to
show what consequences should follow from the
above conception of the ether, from an experi-
mental or realistic point of view, even should it
never be possible to isolate or combine or in any
way grasp this substance.

Although it was possible to approximately
determine the atomic weight of the element y
on the basis of that of helium, this cannot be
repeated for the element a?, because it lies at the
frontier or limit, about the zero point of the atomic
weights. Moreover, the analogues of helium

D

34 A CHEMICAL CONCEPTION OF THE ETHER

cannot serve as a basis owing to the uncertainty of
their numerical data. However, if the ratio of the
atomic weights be Xe : Kr=T56 : 1 ; Kr : Ar=
2 # 15 : 1 ; and Ar : He=9*5 : 1, we find that He : x
= 28'6 : 1 ; or if He=4'0, that the atomic weight
of <r=0'17. This must be considered the maxi-
mum possible value. Most probably the atomic
weight of x is far less, for the following reasons.
If the gas in question be an analogue of helium,
its molecule will contain one atom, and there-
fore its density, referred to that of hydrogen,

must be about half its atomic weight or -, where

x is the atomic weight. In order to be able to
permeate throughout all space, its density must be
so small, compared with that of hydrogen, that
its molecular motion would allow it to overcome
the attraction, not only of the earth and sun, but
also of all the stars, as otherwise it would
accumulate about the largest mass and not fill
all space. The velocity of the molecular motion
of a gas by which the gaseous pressure is deter-
mined — by the number of impinging particles
and their vis viva — is calculated according to the
kinetic theory of gases, by an expression con-
taining a constant divided by the square root of
the density of the gas and multiplied by the

H

A CHEMICAL CONCEPTION OF THE ETHER 35

square root of (1 + at) whichjexpresses the expan-
sion of the gas by heat. In the case of hydrogen
(density = 1) at £=0°, the mean velocity of the
particles, calculated on the basis that a litre of
hydrogen at 0° and 760 m.m. weighs about # 09
grms., is 1843 metres a second, that of oxygen
being 461 m&tres, for its density is 16 times

that of hydrogen, i.e. v = —7—= *61. Thus the

velocity increases as the density becomes less and
as the temperature becomes greater, but does not
depend upon the number of molecules in a given
volume ; and if our gas have an atomic weight x

and density (referred to hydrogen) -, then the
velocity of its molecules will be :

t;=1848>y 2 Il^) . . . (1)
v x

In this expression x is the unknown quantity, to
find which we must know t and v 9 or the velocity
required by the particles to escape from the
sphere of the earth's, sun's, and stars' attraction,
like the projectile in Jules Verne's * Voyage to
the Moon.'

As regards the temperature of space, this can
only be regarded as the absolute zero by those
who deny the material nature of the ether, for

D 2

36 A CHEMICAL CONCEPTION OF THE ETHER

temperature in a perfect vacuum or in space
devoid of matter is an absurdity, and a solid such
as an aerolite or thermometer introduced into such
space would alter the temperature, not by contact
with the surrounding medium, but solely by radia-
tion. But if space be filled with the substance of
ether, it not only may, but must, have its own tem-
perature, which evidently cannot be absolute zero.
Many methods have been tried to determine this
temperature, but it is unnecessary to discuss
them here. Suffice it to say that no one has
found it less than —150° or above —40°; as a
rule, the limits are taken as —100° and —60°.
It is hopeless to expect any definite or exact
data on this subject, and probably the tem-
perature varies in different localities owing to
radiation being different in different parts of
space. Moreover, the value of t between —100°
and —60° has hardly any significance in an
approximate evaluation of x> as only the maxi-
mum value of x can be calculated by the
expression (I) ; for there can be no question of
any exact value, all that is required being to
obtain an idea of the order in which x stands
among the elements. We therefore take the
mean temperature t = — 80 ; then if a= 0*000867,

2191 4800000 /TTV

U— -7= or x= s— . . (II)

A CHEMICAL CONCEPTION OF THE ETHER S7

where x is the atomic weight of the gaseous
element required, referred to hydrogen, and v
the velocity of motion of its particles at —80° in
metres per second.

This velocity must now be determined. We
know that a body thrown up in the air falls
back to the earth, and in so doing describes a
parabola. The height of its flight increases as
its initial velocity is made greater, and it is
evident that this velocity might be such that the
body would pass beyond the sphere of the earth's
attraction, and fall on some other heavenly
body, or rotate about the earth as a satellite by
virtue of the laws of gravitation. It has been
calculated that to do this the velocity of the
body must exceed the square root of double the
mass of the attracting body divided by the
distance from its centre of gravity to the point
at which the velocity is to be determined. The
mass of the earth is calculated in absolute units
from the mean radius of the earth ( = 6,878,000
metres) and the mean attraction of gravity at
the surface of the earth (= 9-807 metres), for the
attraction of gravity is equal to the mass divided
by the square of the distance (in this instance,
the square of the earth's radius), and therefore
the mass of the earth = 898. 10 12 , and the velocity

38 A CHEMICAL CONCEPTION OF THE ETHER

sought for must therefore exceed 11,190 metres
a second. Hence, according to formula II.,
the atomic weight of such a gas must be less
than 0*038 to enable it to escape freely from the
earth's atmosphere into space. All gases of
greater atomic weight, not only hydrogen and
helium, but even the gas y (coronium?), will
remain in the earth's atmosphere.

The mass of the sun is approximately
325,000, if that of the earth be taken as unity.
Hence the absolute magnitude of the sun's mass
will be nearly 129.10 18 . The radius of the sun
is 109*5 times greater than that of the earth, i.e.
nearly 698. 10 16 metres. Hence only bodies or
particles having a velocity of not less than

2 129 10 18

-or about 608,300 metres a second,

v

698.10 16

could escape from the surface of the sun.
According to formula (II), the atomic weight
of a gas x having such a velocity will not be
greater than 0*000013, and its density will be
half this figure. Hence the atomic weight and
density of such a gas which, like the ether,
permeates space, must at all events be less than
this .figure. This is inevitable because there are
stars of greater mass than the sun. This has been
proved by researches made on the double stars.

A CHEMICAL CONCEPTION OF THE ETHER 39

The most exact data we now possess concern
Sirius, whose total mass (including that of its
satellites) is 3*24 times that of the sun. To
determine this, it was necessary to investigate
not only the relative motion of both stars, but
also the parallax of this system. In the case of
Sirius it was possible to determine the ratio ot
the masses of the two stars. This was found to
be 2*05, so that the mass of one star is 2*20, and
that of the other 1*04, times that of the sun. In
the following cases, only the total mass of the
two twin stars was determined relative to that of
the sun :

d Centauri 2-0

70 Ophiuchi 1-6

fi Cassiopeiae 0*52

61 Cygni . 0-34

y Leonis ....... 5*8

y Virginis 3270

The mass of Persei with its satellites is
0*67 times that of the sun, that of the star being
twice that of its satellite. The triple star 40
Eridium has a mass 1*1 times that of the sun,
the mass of the brightest star being 2*37 times
that of the other two.

It appears, therefore, that although there are
some stars which are greater, and some which
are less, still the mass of the sun is nearly the

*

r

40 A CHEMICAL CONCEPTION OF THE ETHER

average of that of the other stars. For our
purpose we need only consider the stars of
much greater mass than the sun. That of the
double star y Virginis has a common mass about
38 times that of the sun. There is no reason
for thinking that this is the maximum, and
it will therefore be safer to infer that there
may be stars whose mass exceeds 50 times that
of the sun, but I do not think it likely that a
larger mass than this is in the nature of things.
To complete our calculation it is also necessary
to know the radius of the stars, about which we
have no direct data. However, the composition
and temperature of the stars may give a clue.
Spectrum analysis proves that the terrestrial
chemical elements occur in the most distant
heavenly bodies, and from analogy there seems no
doubt that the general mass composition of these
bodies is very similar in all cases ; that is to say,
that they are composed of a dense core surrounded
by a less dense crust and an atmosphere which
becomes gradually rarefied. Thus the composi-
tion of the stars probably differs but little from
that of the sun. And the density is determined
by the composition, temperature, and pressure.
Only at the core can the density differ much from
that of the sun, but this cannot greatly affect

A CHEMICAL CONCEPTION OF THE ETHER 41

the average density. Neither can the tem-
perature of the stars differ greatly from that of
the sun. Moreover, a rise of temperature would
tend to increase the diameter of the star, and
this would decrease the value of the velocity
required by the gaseous particles to escape from
the sphere of attraction. It appears, therefore,
that for the purposes of our calculation the average
density of the large stars may be taken as nearly
that of the sun, and therefore that the radius of a
star whose mass is n times that of the sun will be
l/n times the radius of the sun. We now have
all the data necessary for calculating the velocity
required by gaseous particles to escape from the
sphere of attraction of a star 50 times greater
than the sun.

Its mass is 50.129.10 18 or nearly 65.10 29 , and
its radius nearly 698.10 6 £/50 or 26.10 8 . Hence
the velocity required will be nearly :

V

' o = 2,240,000 metres per second.

26 x 10 8 F

or 2,240 kilometres per second.

The great magnitude of this velocity, v 9 and
its proximity to that of light (800,000,000
metres a second) provoke the following inquiry.
How much must the mass of a heavenly body

42 A CHEMICAL CONCEPTION OF THE ETHER

exceed that of the sun in order to retain on its
surface particles endowed with a velocity of
8.10 s metres per second, if its mean density
were equal to that of the sun ? This may be
calculated from the fact that if the mean density
of the two luminaries be equal, the velocities of
bodies able to escape into space from the spheres
of attraction will stand in the ratio of the cube
roots of their masses, and therefore a luminary
from whose surface particles endowed with a
velocity of 300,000,000 metres per second could
escape must have a mass 120,000,000 times that
of the sim, for only particles having a velocity of
608,000 metres a second can escape from the sun,
and this stands to 300,000,000 in the ratio 1 : 493,
and the cube of 493 is nearly 120,000,000.

But, so far we have no reason for admitting
the existence of such a huge body, and therefore
it seems to me that the velocity of the particles of
our gas (ether) must, in order to permeate space,
be greater than 2,240,000 metres a second and
probably less than 300,000,000 metres a second.

Hence the atomic weight of x as the lightest
elementary gas, permeating space and perform-
ing the part of the ether, must be within
the limits (formula II) of 0-000,000,96 and
0000,000,000,058, if that of H - 1.

A CHEMICAL CONCEPTION OF THE ETHER 43

I think it is impossible, under the present
conditions of our scientific knowledge, to admit
the latter value, because it would in some
measure answer to a revival of the emission
theory of light, and I consider that the majority
of phenomena are sufficiently explained by the
fact that the particles and atoms of the lightest
element x capable of moving freely everywhere
throughout the universe have an atomic weight
nearly one millionth that of hydrogen, and travel
with a velocity of about 2,250 kilometres per second.

When I was making these calculations, my
friend Professor Dewar sent me his presidential
address to the Belfast meeting of the British
Association. In it he expresses the thought
that the highest regions of the atmosphere, which
are the seat of the aurora borealis, must be
considered to be the province of hydrogen and
of the argon analogues. This is only a few
steps from the yet more distant regions of
space, and from the necessity of recognising
the existence of a still lighter gas capable of
permeating and filling space and thus giving a
tangible reality to the conception of the ether.

In conceiving of the ether as a gas endowed
with the above properties, and belonging to the
zero group of elements, I desired before all to

44 A CHEMICAL CONCEPTION OF THE ETHER

extract from the periodic law that which it was able
to give and to tangibly explain the materiality
and universal presence of an ethereal substance
throughout nature, and also to explain its faculty
of permeating all substances, gaseous, liquid, and
solid. The atoms of even the lighter elements
forming the ordinary substances being several
million times heavier than those of ether, they
are not likely to be greatly influenced in their
mutual relations by its presence.

Of course there are still many problems to
be solved, but I think the majority are un-
fathomable, and I have no intention of raising
them here or of trying to solve those which
appear capable of being solved. My only pur-
pose has been to state my opinion on a subject
about which I know many are thinking and some
are beginning to speak.

Without going into a further development
of our subject, I should like to acquaint the
reader with some, at first sight, auxiliary cir-
cumstances which guided my thoughts and led
me to publish my opinions. These consist of a
series of recently discovered physico-chemical
phenomena which are not subject to the ordinary
doctrines of science, and have caused many to
return to the emission theory of light, or to

A CHEMICAL CONCEPTION OF THE ETHER 45

accept the, to me, vague hypothesis of electrons,
without trying to explain to the utmost the
familiar conception of an ethereal medium trans-
mitting luminous vibrations, &c. This more
especially refers to radio-active phenomena.

I need not describe these most remarkable
phenomena, assuming that the reader is more or
less acquainted with them ; and will only mention
that a perusal of the literature of the subject,
and what I saw in M. Becquerel's laboratory
{md heard from him and Monsieur and Madame
Curie, gave me the impression of some peculiar
state proper chiefly (but not exclusively, just
as magnetism is chiefly, but not exclusively, the
property of iron and cobalt) to uranium and the
thorium compounds.

As uranium and thorium, and also radium,
judging from Madame Curie's researches (1902),
have the highest atomic weights (U=289, Th=
282, and Rd=224) among the elements, they may
be looked upon as suns, endowed with the
highest degree of that individualised attractive
capacity, a mean between gravity and chemical
affinity, which is seen in the absorption of gases,
solution, &c. By conceiving the substance of the
ether as the lightest of gases, x 9 deprived, like
helium and argon, of the power to form stable

46 A CHEMICAL CONCEPTION OF THE ETHER

definite compounds, it need not be imagined
that this gas is deprived of the faculty of, as it
were, dissolving in or accumulating about large
centres of attraction like the sun among heavenly
bodies, or uranium and thorium in the world of
atoms. As a matter of fact, direct experiment
proves that helium and argon are able to dissolve
in liquids, and, moreover, to individualise this
faculty according to either their own nature or
that of the liquid and according to the tempera-
ture. If the ether is a gas, #, it must naturally
accumulate from all parts of the universe towards
the medium or mass of the sun, just as the gases
of the atmosphere accumulate in a drop of water.
And the lightest of gases, #, will also accumu-
late about the heaviest atoms of uranium and
thorium, and perhaps change its form of motion
like a gas dissolved in a liquid. This will not be
a definite act of combination, determined by a
conformable harmonious motion, like the motion
of a planet and its satellites, but an embryo of
such a motion, resembling that of a comet in the
region of heavenly individualisations, and it may
be looked for sooner in the region of the heaviest
atoms of uranium and thorium than in those
of the lighter elements, just as a comet falling
from space into the planetary system revolves

A CHEMICAL CONCEPTION OF THE ETHER 47

round the sun and then once more escapes
into space. If such a special accumulation
of ether atoms about the molecules of ura-
nium and thorium be admissible, they might
be expected to exhibit peculiar phenomena,
determined by the emission of a portion of this
ether held by particles of normal mean velocity
and by new ether entering into the sphere of
attraction. It seems to me that the optical and
photo-radiant phenomena, not to mention the loss
of electrical charges, indicate a material flow of
something which has not been weighed, and it
appears to me that they might be understood
in this manner, for peculiar forms of the
entrance and egress of ether atoms should be
accompanied by such disturbances in the
ethereal medium as give the phenomena of light.
Monsieur and Madame Curie showed me the
following experiment, for instance. Two small
flasks were connected together by a lateral tube
fused into their necks, and having a stop-cock in
the middle. The cock being closed, a solution of
the radio-active substance was poured into one
of the flasks, while a gelatinous white precipitate
of sulphide of zinc, shaken up in water, was
placed in the other flask. Then both flasks
were closed. So long as the cock between the

48 A CHEMICAL CONCEPTION OF THE ETHER

flasks remains closed, nothing is visible in the
dark ; but directly it is opened, the sulphide of
zinc becomes brilliantly fluorescent and continues
so as long as the tube connecting the flasks re-
mains open. This experiment gives the im-
pression of an emissive flow of something
material from the radio-active substance, and, in
a sense, seems comprehensible if we assume that
a peculiar rarefied ether gas, capable of exciting
luminous vibrations, enters and passes off from
the radio-active substance. Just as any kind of
motion may be set up in a gas, not only by a
solid piston, but also by the motion of another
portion of the same gas, so also the phenomenon
of light, i.e. a certain transverse vibration of
ether, may be produced not only by the
molecular motion of particles of other bodies
(by heating them or otherwise) bringing the
ether from its state of mobile equilibrium, but
also by a certain change in the motion of the
ether atoms themselves ; i.e. by their destroying
their own equilibrium which may be caused in the
case of the radio-active bodies by the massiveness
of the atoms of uranium and thorium, just as
the luminosity of the sun may be, I think, due
to its great mass being able to accumulate ether
in far larger quantities than the planets, &c. I

A CHEMICAL CONCEPTION OF THE ETHER 49

think that the radio-luminous phenomena, i.e.
such as proceed at right angles to the ray of the
vibration of the ether medium, consisting of
minute atoms in rapid motion, are, as a matter
of fact, more complex than has hitherto been
thought, chiefly owing to the fact that the velocity
of the ether atoms is not very much less (130
times) than that of the propagation of their
transverse vibrations. This at all events was the
impression I acquired from the radio-active
phenomena I saw, and I do not conceal it,
although I consider it very difficult to form
any opinion on this still dim province of the
phenomena of light.

In conclusion, I may mention another class of
phenomena, which led me to this conception of
the ether. Dewar, about 1894, in his researches
on the phenomena proceeding at low tem-
peratures, observed that the phosphorescence of
many substances, and especially of paraffin, be-
comes more intense at the temperature of liquid
air (between — 181° and — 198°). Now, it appears
to me that this is due to the fact that paraffin
and such like substances have a great capacity
for condensing the atoms of ether at very low
temperatures. In other words, that the solubility
(absorption) of the ether in some bodies increases

E

. I

50 A CHEMICAL CONCEPTION OF THE ETHER

in extreme cold. They therefore become more
phosphorescent, for the vibrations of light are
then set up in the phosphorescent substances,
not only by their own atoms (having the
property of illumination at their surface, of
passing into a state of peculiar tension, which
causes, when the act of illumination ceases, the
ether to vibrate), but also by the atoms of ether
which condense in these bodies and set up a
rapid state of interchange with the surrounding
medium.

It seems to me that this conception of ether,
as a peculiar all-permeating gas, gives a means,
if not of analysing such phenomena, at all events
of understanding their possibility. I do not
regard my imperfect endeavour to explain the
nature of ether from a chemical point of view
as more than the expression of a series of
thoughts which have arisen in my mind, and
which I have given vent to solely from a desire
that these thoughts, being suggested by facts,
should not be utterly lost. Most probably
similar thoughts have come to many, but unless
they are enunciated they often pass away
without being further developed. If they con-
tain a particle of that natural truth which we
all seek, my effort will not have been in vain ; it

A CHEMICAL CONCEPTION OF THE ETHER 5 J

may then be worked out, embodied and corrected,
and if my conception be proved false in its basis,
it will prevent others from repeating it. I know
of no other way for slow and steady progress.
And even if it be found impossible to recognise
in the ether the properties of the lightest, most
mobile, and chemically inactive gas, still, if we
keep to the realism of science, we cannot deny
its substantiality, and this requires a search for
its chemical nature. My effort is no more than
a tentative answer to this primary question, and
its one object is to bring this question to the
fore.

October 1902.

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