190 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1911. 
allotropes or pseudoelements; this leaves 16, for which 16 or 17 gaps 
would appear to be available in the periodic table, provided the reas- 
onable supposition be made that a second change in the length of the 
periods has taken place. It is above all things certain that it would 
be a fatal mistake to regard the existence of such elements as irrecon- 
cilable with the periodic arrangement, which has rendered to sys- 
tematic chemistry such signal service in the past. 
Attention has repeatedly been drawn to the enormous quantity of 
energy stored up in radium and its descendants. That in its emana- 
tion, niton, is such that if what it parts with as heat during its disin- 
tegration were available, it would be equal to three and a half million 
times the energy available by the explosion of an equal volume of 
detonating gas—a mixture of 1 volume of oxygen with 2 volumes of 
hydrogen. The major part of this energy comes apparently from 
the expulsion of particles (that is, of atoms of helium) with enormous 
velocity. Itis easy to convey an idea of this magnitude in a form 
more realizable by giving it a somewhat mechanical turn. Suppose 
that the energy in a ton of radium could be utilized in 30 years instead 
of being evolved at its invariable slow rate of 1,760 years for half- 
disintegration, it would suffice to propel a ship of 15,000 tons, with 
engines of 15,000 horsepower, at the rate of 15 knots an hour for 30 
years, practically the lifetime of a ship. To do this actually requires 
14 million tons of coal. 
It is easily seen that the virtue of the energy of the radium consists 
in the small weight. in which it is contamed; in other words, the 
radium-energy .is in an enormously concentrated form. I have 
attempted to apply the energy contained in niton to various purposes; 
it decomposes water, ammonia, hydrogen chloride, and carbon 
dioxide, each into its constituents; further experiments on its action on 
salts of copper appeared to show that the metal copper was con- 
verted partially into lithium, a metal of the sodium column; and 
similar experiments, of which there is not time to speak, indicate that 
thorium, zirconium, titanium, and silicon are degraded into carbon; 
for solutions of compounds of these, mixed with niton, invariably 
generated carbon dioxide; while cerium, silver, mercury, and some 
other metals gave none. One can imagine the very atoms themselves 
exposed to bombardment by enormously quickly moving helium 
atoms failing to withstand the impacts. Indeed, the argument a 
priori is a strong one; if we know for certain that radium and its 
descendants decompose spontaneously, evolving energy, why should 
not other more stable elements decompose when subjected to enor- 
mous strains ? 
This leads to the speculation whether, if elements are capable of 
disintegration, the world may not have at its disposal a hitherto 
unsuspected source of energy. If radium were to evolve its stored-up 
