On the chemical side... work of M. and Mme. Curie had shown radioactivity to be a specific atomic property... restricted to the last two... then known elements, and , though... and emit β-rays, exhibiting in this respect... radioactivity. Using the new property much as the pioneers with the spectroscope used the spectra in the discovery of new elements, they discovered the powerfully radioactive... and , and, M. Debierne, , in the uranium minerals.
— FREDERICK SODDY