Elements Occupying the Position of No. 61

Abstract

A RECENT investigation has resulted in the finding of actinium¹ accumulated between neodymium and samarium magnesium nitrates after fractional crystallization; that is, between elements Nos. 60 and 62. I have carried out a separation of the above two salts, but with the addition and aid of the isomorphous bismuth magnesium nitrate. This last, using as solvent the weakest possible nitric acid, is intermediate in solubility between neodymium and samarium, and not appreciably more soluble than samarium, as when stronger acid is used. It was thus possible to reduce the neodymium–samarium intermediates from several kilograms of oxides almost to vanishing point. The products were examined by Drs. Collie and Roaf in the Clarendon Laboratory, Oxford, in 1937. The now well-established radioactivity of samarium was confirmed, but the small intermediate fractions were found to possess a stronger activity. This was eventually traced to thorium through determination of the half-life of the emanation.