_ 
. 
4 
Sept. 2, 1886] 
only. Coincident with the creation of atoms all those attributes 
and properties which form the means of discriminating one 
chemical element from another start into existence fully endowed 
with energy. 
The pendulum begins its swing from the electro-positive side ; 
- lithium, next to hydrogen in simplicity of atomic weight, is now 
formed ; then glucinum, boron, and carbon. Definite quantities 
of electricity are bestowed on each element at the moment of 
birth, on these quantities its atomicity depends,! and the types 
of monatomic, diatomic, triatomic, and tetratomic elements are 
fixed. The electro-negative part of the swing now commences ; 
nitrogen appears, and notice how curiously position governs the 
mean dominant atomicity. Nitrogen occupies the position below 
boron, a triatomic element, therefore nitrogen is triatomic. But 
nitrogen also follows carbon, a tetratomic body, and occupies 
the fifth position counting from the place of origin ; how beauti- 
fully these opposing tendencies are harmonised by the endow- 
ment of nitrogen with at least a double atomicity, and making 
its atom capable of acting as tri- and pentatomic. With oxygen 
(di- and hexatomic) and fluorine (mon- and heptatomic) the same 
law holds, and one half-oscillation of the pendulum is completed. 
Again passing the neutral line the electro-positive elements, 
sodium (monatomic), magnesium (diatomic), aluminium (tri- 
atomic), and silicon (tetratomic) are successively formed, and 
the first complete oscillation of the pendulum is finished by the 
birth of the electro-negative elements phosphorus, sulphur, and 
chlorine ; these three—like the corresponding elements formed 
on the opposite homeward swing—having each at least a double 
atomicity depending on position. 
Let us pause at the end of the first complete vibration and 
examine the result. We have already formed the elements of 
water, ammonia, carbonic acid; the atmosphere, plant and 
animal life, phosphorus for the brain, salt for the sea, clay for the 
solid earth, two alkalies, an alkaline earth, an earth, together with 
their carbonates, borates, nitrates, fluorides, chlorides, sulphates, 
phosphates, and silicates, sufficient for a world and inhabitants 
not so very different from what we enjoy at the present day. 
True the human inhabitants would have to live in astate of more 
than Arcadian simplicity, and the absence of calcic phosphate 
would be awkward as far as bone is concerned. But what a 
happy world it would be! No silver or gold coinage, no iron 
_ for machinery, no platinum for chemists, no copper wire for 
telegraphy, no zine for batteries, no mercury for pumps, and, 
alas! no rare earths to be separated. 
The pendulum does not, however, stop at the end of the first 
complete vibration ; it crosses the neutral point, and now the 
forces at work are in the same position as they were at the be- 
ginning. Had everything been as it was at first the next ele- 
-ment again would have been lithium, and the original cycle 
would have recurred, repeating for ever the same elements. 
But the conditions are not quite the same ; the form of energy 
represented by the vertical line has declined a little—the tem- 
perature has sunk—and not lithium, but the one next allied to it 
in the series comes into existence—potassium, which may be 
regarded as the lineal descendant of lithium, with the same 
hereditary tendencies, but with less molecular mobility and 
higher atomic weight. 
Pass we rapidly along the to-and-fro curve, and in nearly 
every case the same law is seen to hold good. The last element 
_of the first complete vibration is chlorine. In the corresponding 
place in the second vibration we do not have an exact repetition 
of chlorine, but the very similar body bromine ; and when for a 
third time the position recurs we see iodine. I need not 
multiply examples. 
In this far-reaching evolutionary scheme it could not come to 
pass that the potential elements would all be equal to one 
another. Some would be unable to resist the slightest disturb- 
ance of the unstable equilibrium in which they took their rise ; 
others would endure longer, but would ultimately break down 
as temperature and pressure varied. Many degrees of stability 
* “Nature presents us with a single definite quantity of electricity. . . . 
For each chemical bond which is ruptured within an electrolyte a certain 
quantity of electricity traverses the electrolyte, which is the same in all 
cases.” —G,. JOHNSTONE STonery, ‘‘On the Physical Units of Nature,’’ 
British Association Meeting, 1874, Section A. P/i/. Mag., May 1881. 
“The same definite quantity of either positive or negative electricity 
moves always with each univalent ion, or with every unit of affinity of a 
multivalent ion.”—HELMHOLTZ, Faraday Lecture, 188r. 
“Every monad atom has associated with it a certain definite quantity of 
electricity ; every dyad has twice this quantity associated with it; every 
triad three times as much, and so on.’”’—O. Loncr, ‘On Electrolysis,” 
a British Association Report,” 1885. 
NATURE 
4 
at 
would be here represented ; not all the chemical elements are 
equally stable, and if we look with scrutinising eyes we shall 
still see our old friend the missing link, coarse enough to be 
detected by ordinary chemical processes, associated in the groups 
containing such elements as iron, nickel, and cobalt ; palladium, 
ruthenium, and rhodium; iridium, osmium, and_ platinum. 
Whilst in their more subtile form these missing links present 
themselves as representatives of the differences which I have 
detected and described between the atoms of the same chemical 
element. 
Dr. Carnelley has pointed out that ‘‘ those elements belonging 
to the even series of Mendeléeff’s classification are always para- 
magnetic, whereas the elements belonging to the odd series are 
always diamagnetic.” On this curve the even series to the left, 
as far as can be ascertained, are paramagnetic, and, with a few 
exceptions, all to the right are diamagnetic. The very powerful 
magnetic metals, iron, nickel, cobalt, and manganese, occur 
close together on the proper side. The interperiocic groups, of 
which palladium and platinum are examples, are said to be 
feebly magnetic, and, if so, they form the exceptions. Oxygen, 
which weight for weight is more magnetic than iron, comes near 
the beginning of the curve, while the powerfully diamagnetic 
metals, bismuth and thallium, are at the opposite end of the 
curve. 
On the odd, or diamagnetic, half of the swing the energy 
appears to have considerable regularity, whilst it is very irregular 
on the opposite side of the curve. Thus, between the extreme 
odd elements, silicon (28), germanium (73), tin (118), the miss- 
ing element (163), and lead (208), there is a difference of exactly 
45 units, conferring remarkable symmetry on one half of the 
curve. The differences on the even side are 36, 42, 51, 39, and 
53 (giving the missing element between cerium and thorium an 
atomic weight of 180) ; these at first sight appear conformable 
to no law, but they become of great interest when it is seen that 
the mean difference of these figures is almost exactly the same 
as that on the other side of the curve—viz. 44°2. 
This uniformity of difference—actual on the one side and 
average on the other—brings out the important inference that, 
whilst on the odd side there has been little or no variation in 
the vertical force, minor irregularities have been the rule on the 
even side. That is to say, the fall of temperature has been very 
uniform on the odd side—where every element formed during 
this half of the vibration is the representative of a strongly- 
marked group—sodium, magnesium, aluminium, silicium, phos- 
phorus, sulphur, and chlorine; whilst on the even side of the 
swing the temperature has sunk with considerable fluctuations, 
which have prevented the formation here of any well-marked 
groups of elements, with the exception of those of which lithium 
and glucinum are the types. 
If we can thus trace irregularities in the fall of temperature, 
can we also detect any variation in the force represented by 
the pendulous movement? I have assumed that this represents 
chemical energy. In the early-formed elements we have those 
in which chemical energy is at its maximum intensity, while, as 
we descend, affinities for oxygen are getting less and the 
chemism is becoming more and more sluggish. Part may be 
due to the lower temperature of generation not permitting such 
molecular mobility in the elements, but there can be little doubt 
that the chemism-forming energy, like the fires of the cosmical 
furnace, is itself dying out. 1 have endeavoured to represent 
this gradual fading out by a diminution of amplitude, the curve 
being traced from a photographic record of the diminution of 
the arc of vibration of a body swinging in a resisting medium. 
When we look on a curve of this kind there is a tendency to 
ask, What is there above and below that portion which is seen ? 
At the lower end of our curve what is there to be noted? We 
see a great hiatus between barium (137) and iridium (192°5), 
which it seems likely will be filled up by the so-called rare ele- 
ments, Judging from my own researches, it is probable that 
many of these earthy elements will be found included in one or 
more interperiodic groups, whilst the higher members of the 
calcium, the potassium, the chlorine, and the sulphur groups, 
together with the elements between silver and gold, cadmium 
and mercury, indium and thallium, antimony and bismuth, are 
still waiting to be discovered. We now come to an oasis in the 
desert of blanks. Platinum, gold, mercury, thallium, lead, and 
bismuth, all familiar friends, form a close little group by them- 
selves, and then after another desert space the list is closed with 
thorium (233) and uranium (240). 
This oasis, and the blanks which precede and follow it, may 
