To Discover an Element That Does Not Exist

Professor E. O. Lawrence gave us a piece of molybdenum plate which had been bombarded for some months by a strong deutron beam in the Berkeley cyclotron. The molybdenum has also been irradiated with secondary neutrons which are always generated by the cyclotron. 

So starts a paper in 1937 [28.3] by E.G. Segre and C. Perrier at the university in Palermo, Italy, a paper that is regarded as the announcement of the real discovery of element 43. Lawrence was the inventor of the cyclotron SegrI, visiting him in Berkeley, was a specialist in the chemistry of radioactive elements and Perrier was a mineralogist and colleague to Segre. 

Visiting the radioactive molybdenum plate in its protective container Segre must have had the following reactions in his thoughts  

Returning to Palermo, Segre and Perrier started an investigation of the molybdenum plate. 

200 mg of the Mo plate was dissolved in aqua regia. The solution was very radioactive. Manganese and rhenium compounds were added as carriers. The two scientists could show that the radioactivity followed these elements in chemical reactions. They supposed that they had element 43 in their beakers. 

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