On the spectra of ordinary lead and lead of radioactive origin

Abstract

The view that the spectra of isotopes are identical was first put to the test by Russell and Rossi and Exner and Hascheck, who examined the spectra of thorium and ionium preparations. The former of these observers worked with a mixture containing at least 10 per cent. Of ionium, but no lines were found which were not present in the spectrum of pure thoria. Aston has submitted neon to fractional diffusion, by which a partial separation was effected, as shown by the change of density, but no change in the spectrum was observed.