The Natural Beta-Ray Spectrum of RaD

The natural $\beta$-ray spectrum of RaD has been photographed and the energies of its lines directly compared with those of the RaB $\beta$-ray spectrum in the same region. The RaB line $H\rho =660.9\mathrm{}$ as measured by Ellis and ${\mathrm{Skinner}}^1$ has been taken as a standard reference line. The following values for the energies of the lines have been determined: No. 5 is a line which has previously escaped detection. The analysis of this spectrum for determining the energy of the $\gamma$-ray responsible for it shows conclusively that the $\gamma$-ray is emitted after the disintegration. This is in accord with ${\mathrm{M}\mathrm{e}\mathrm{i}\mathrm{t}\mathrm{n}\mathrm{e}\mathrm{r}\text{'}\mathrm{s}}^2$ view. The energy of the $\gamma$-ray is determined as 0.467×${10}^5$ volts.