THE ROMANCE OF RADIUM.*
PRO. FESSOR SODDY, who is one of the greatest living authorities on the new science of radioactivity, has just published a, very readable collection of _Addresses and articles written during• the last five years. In most of these he aims at defining the relation of his special field of inquiry to the general problems of life and thought, and the thoughtful layman will find them eminently worthy of study: Specially interesting to those who wish to know what light has been thrown upon the inmost secrets of matter in the last few years are the three papers entitled "Science and Life," "The Evolution of Matter," and "The Conception of the Chemical Element as Enlarged by the Study of Radioactive Change." Professor Soddy remarks with truth that "the future race will date the coming in of its kingdom from the discovery of radium, mainly due to a woman." It is barely twenty years since Mine. Curie, working along the track indicated by Henri Becquerel's researches into certain properties of uranium compounds, first discovered that an extraordinary • science and Life. By Frederick Sodd.y. M.A.. F.B.S. London; Murray [10s. lki. net.'
power of constantly emitting energy without any obvious source characterized the new element which she christened radium.
This element gives out enough heat to raise hi own weight of water from the freezing to the boiling point in about three- quarters of an hour, without itself suffering any apparent loss. In two days it gives out as much energy as would be obtained from the complete combustion of the same weight of coal, and _this emission of energy has gone on without any measurable diminution during the twenty years in which radium has been watched. We know now, of course, that this marvellous pro- perty is not, as some rash persons at first inferred, in any way contradictory of the fundamental principle of the conservation of energy. As in all other cases yet known, a price has to be paid for the work done by the radium, and this price is paid by the gradual degradation of its atoms. With the lapse of cen-
turies, a given portion of radium will cease to exist, having spent itself in labour and changed into inert elements ; but before that end to its activities arrives, it will have given out more than three hundred thousand times as much energy as could be obtained from the combustion of the same weight of coal. If we could devise any method for liberating this energy at our
will, a few pounds of radium would suffice to drive a steamship across the Atlantic, and an airman could carry in his pockets enough fuel for a trip round the world.
At present, however, no such possibility is within actual sight. One of the most curious features of radioactive changes is that they cannot be modified by any conditions as yet known:—
" The whole phenomena are inevitable, incapable of being changed or deviated from their allotted course by any means whatever, independent of temperature, concentration, or the accumulation of products of reaction, the presence of catalysts, irreversible and capable of being accurately and quantitatively followed without alteration or disturbance of the changing system."
They differ in this respect from so-called chemical changes, as well as in the magnitude of the energy evolved, which surpasses that known in the most violent chemical reactions—such as the detonation of T.N.T.—as much as a millionfold. In radio- activity we have been introduced to an altogether new world of
knowledge, which deals with the things that happen inside the chemical atoms. We now know with certainty that certain atoms are miniature solar systems, a central massive nucleus or sun surrounded by tiny and almost immaterial electrons or planets in rapid orbital motion ; and it is a great probability that even the atoms which show no signs of radioactive change
have a similar though a more stable constitution. The radio- active change itself is simply a splitting up of the system, due to the sudden departure of a portion of the central sun or one Of the planets into the outer space where it becomes amenable to the subtle methods of the modern laboratory—methods sur- passing in delicacy those of the test-tube, the balance, or the
spectroscope to an almost incredible extent, and permitting the student to work with literally invisible fragments of matter towards a valid conclusion. The radioactive elements are all in process of transmutation, at very varying rates. Uranium takes over a thousand million years to change completely, while some of the more elusive elements have so brief a life that light itself would travel only a few yards between their birth and death. It is a remarkable fact that only two final products of all these changes are as yet known, the rare and inert gas helium and the metal lead. It is a mere accident that gold is not one of the products, being just missed at a certain stage in the process, so that the old alchemists were not so far deceived. .For financial purposes it is a good thing that this is so, since lead varies in atomic weight by nearly one per cent according to whether it originates from uranium or thorium, and if this were the case with gold a bank cashier might be a pound or two out in making a payment of two or three hundred sovereigns by weight—if the day ever recurs when that will be done. Far more valuable than gold, however, is the possible source of energy for all the world's work which is indicated by the dia. coveries of the last twenty years. We are still on the threshord of the science of radioactivity, and one cannot but hope that within the next century we may discover some means of turning to useful account the vast stores of intra-atomic energy which lie all about us. "Already," says Professor Soddy, "the quarry is in full view and, by numerous routes, investigators are starting off in hot pursuit. . . . It is unlikely, but not impossible, that such a discovery might be made almost at Once." Let us hope that, before that occurs, the World will have taken to heart Professor Soddy's plea that such a discovery may be turned to
the uses of peace and not of war—that physical force may be no longer the master but the servant of mankind.
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