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Show Science, Like Law, Has Own kTureau of Missing Persons" Hunt Is On Now for Long I.ot l'arents of Aetinium Rochester, N. Y. The police po-lice may have their missing persons bureaus who hunt for the Charley Rosses and Judge Craters of the world but science too has similar mysteries and none so famous fa-mous as the "missing" parents par-ents of the element actinium. From heaviest of all elements, uranium, down through radium to lead, the atoms undergo a step by step disintegration and "begat" order or-der that reads like a scientific old testament. Just as there is a "missing link" in the hypothesis of animal evolution evolu-tion between the npes and modern man so too is there a theoretical stone out of place in the structure which welds the whole of radioactivity radioactiv-ity theory into a compact unit. How Lost Are Traced. In a report to the American Physical Phys-ical society. Prof. T. R. Wilkins and Dr. W. M. Rayton of the University of Rochester present new evidence which helps make clearer the origins ori-gins of the missing long-lived parents par-ents of the aetinium series of radio-elements. radio-elements. Scientific happenings which make it possible to throw light on the atomic "missing persons" problem are that sometimes the change from one element to another is accompanied accom-panied by a loss of weight and sometimes some-times merely by a loss of electrical charge without the weight loss. The loss of weight occurs when the nucleus of a helium atom, known as an alpha particle, is liberated lib-erated in the radioactive disintegration. disintegra-tion. Then, the parent atom drops down two whole numbers in the numerical scale which rates chemical chem-ical element from hydrogen, at one. to uranium at 92, When electricity is given off by the emission of an electron the atomic number of the element jumps back up the scale by one unit Thus Uranium I (92) gives off an alpha particle and becomes Uranium Ura-nium X, (90). But Uranium X, gives off an electron and becomes Uranium X with atomic number 91. Radium Best Known. Thus in stepwise fashion, but sometimes up and sometimes down the scale of atomic numbers, go the disintegrations of the heavy radioactive radio-active elements, of which the best known is, perhaps, radium with atomic number 83. Common, gray and soft lead are the final offspring of all these spontaneous changes and there are four different kinds of lead; radium lead, thorium lead, actinium lead and just lead. The radium, thorium and actinium here mean that it is lead which had each of these specific origins. Plain lead merely means that scientists cannot can-not specifically fix its origin. The ability of the radioactive atoms to lose or take on weight at various stages means that there will frequently be two or more varieties all having the same chemical properties prop-erties but slightly different masses even though they may have the same atomic number rating. Thus Uranium X, and its three isotopes (as they are known) all have atomic weight of 234. One has an atomic number of 90, another is number 92 and two are number 91. While chemical methods are not sufficiently exact to permit distinguishing distin-guishing between all these varieties, other methods, and in particular, the range with which alpha particles are emitted, serve as experimental checks. Drs. Wilkins and Rayton have studied the alpha particle ranges as their method in seeking actinium's "lost parent." The investigation also al-so throws much needed light on the way alpha particles are emitted from the nucleus of atoms; a problem prob-lem which has bearing on the much-studied much-studied and important field of the constitution of the inner cores of atoms. Details of the methods used will interest scientists but need not necessarily nec-essarily be presented for the layman. lay-man. Suffice it to say that a previ-ously-unfound isotope of uranium has been indicated, at least tentatively, tenta-tively, which might well serve as the parent for the now-orphaned series se-ries of actinium radio-elements. |