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. It is 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 

 lij 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 contained; 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 



