Explanatory notes
… in their radioactive isotopes (K 40, Rb 87, Sm 147, Lu 176, respectively), are to be considered as radioactive … potassium 40, rubidium 87, samarium 147, and lutetium 176 already mentioned, may be added uranium 235 and uranium … 109, iodine 131 and 132, xenon 133, caesium 137, thulium 170, iridium 192, gold 198, and polonium 210. Radioactive …