The isotopic constitution and atomic weights of hafnium, thorium, rhodium, titanium, zirconium, calcium, gallium, silver, carbon, nickel, cadmium, iron and indium

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Abstract
An account of experiments has already been given by which the analyses of the rare earth elements were completed with the aid of a particularly favourable arrangement of the anode ray apparatus. This paper contains a description of analyses of other elements made with the same setting and also of some others subsequently made to obtain more accurate and complete data on elements whose constitution had already been provisionally settled. Results (72) Hafnium —Many previous attempts to obtain the mass spectra of this element had failed. For the most similar element, zirconium, the only successful results had been obtained from the fluoride. A pure sample of hafnium fluoride had been kindly provided by Professor G. v. Hevesy, one of the discoverers of the element, and this was incorporated into the anode mixture. The first trial was a failure; but after the work on zirconium described below a second attempt was made, this time with resolved, so that only rough estimates of abundance could be obtained. These were as follows:— Mass numbers . . . . . 176 177 178 179 180 % abundance . . . . . . 5 19 28 18 30 These given a mean mass number 178·5. Applying the same correction as with the rare earths we get atomic weight of hafnium = 178·4 ± 0·2 in fair agreement with the International value 178·6.