The Masurium File: An X-Ray Mystery. David H. Templeton, Department of Chemistry, University of California, Berkeley, CA 94720-1460.

Walter Noddack, Ida Tacke and Otto Berg [1] reported the discovery of masurium and rhenium, elements 43 and 75, on the basis of weak lines in X-ray spectra excited by electron impact on fractions extracted from niobium and platinum ores. Some or all of these ores contained uranium. Further work produced larger amounts of Re, and it became an item of commerce, but Ma was not detected again. Perrier and Segre [2] are now credited with finding technetium, element 43, as radioactive isotopes made in a cyclotron. Several conjectures may explain how Ma was first observed and then not found again, or else how the authors deceived themselves. It is now known that a longer-lived isotope of Tc, produced by spontaneous fission, occurs naturally in uranium ores, but in concentrations which may, or may not, fall short by several factors of ten from what would have been detected in the Ma experiments [3,4]. Ida Noddack-Tacke [5] published the first suggestion (for which she received little attention or credit) that Fermi's 'new elements' could be products of atomic fission and described how to prove it, five years before the idea was accepted. The stain on her reputation from the masurium affair is likely part of the reason, but by no means all, why her suggestion was disregarded. Time will permit only brief mention of the discovery of fission with its myopia, jealousy, and prelude to war, and its effect on Ida Noddack-Tacke. What can one learn about the X-ray spectra by careful study of the original papers? I will give my conclusions and another conjecture which, if true, would explain this mystery.

1. Naturwissensch. 13, 567 (1925); Z. f. techn. Phys. 6, 599 (1925).

2. J. Chem. Phys. 5, 712 (1937).

3. P. H. M. Van Assche, Nucl. Phys. A480, 205 (1988).

4. G. Herrmann, Nucl. Phys. A505, 352 (1989).

5. Z. f. Angew. Chem. 47, 653 (1934).