ABSTRACT
The experimental analysis of the processes that give rise to the radioactivity of radium have so far not given any evidence of the existence of a stage corresponding to that of thorium X in the case of thorium. The comparative study of the two emanations has settled some points left over in the discussion of the nature of the emanating power of thorium. It has long been known that the activity of the radium emanation decays very slowly and special methods were found necessary for its determination. M. Curie measured the penetrating radiation emitted from a sealed glass tube containing the radium emanation and since the latter gives no penetrating rays, the effect measured was solely due to the excited activity on the walls produced by the emanation. Radium compounds can be de-emanated by ignition and the de-emanated compounds recover their power they are brought into solution, exactly in the same manner as have shown for thorium compounds.
