ABSTRACT
The period of transformation is much longer than that for the corresponding actinium product. The existence of two short-lived products following the emanations of thorium and actinium makes a change of nomenclature desirable, in order to give a definite name to each of these products, and to specify its position in the radioactive series. This chapter discusses the experimental results where there is no evidence that the products considered escape from the negatively charged wire except by the well-known process of radioactive recoil. The scheme of nomenclature proposed, starting from the emanations, is shown in the following table, where the nature of the radiation emitted and the half-value period of transformation are added. There are several modes of transformation possible to account for the observed facts; but it is desirable to delay the discussion of these points until more experimental data are available.
