_Radium E_ is produced from radium D. In breaking up, it emits β (and probably γ) rays but no α rays. It is half transformed in about 6 days and is not so volatile as radium D and F. _Radium F_ is produced from radium E. It emits only α rays and is half transformed in 143 days. This substance in solution attaches itself to bismuth. It is volatile at about 1000° C. Apart from their value and interest in showing the stages of transformation of the radium atom, the results of this analysis have an important bearing upon the origin of some of the well-known radio-active substances separated from pitchblende; for it will be shown later that the product radium F is the radio-active substance present in radio-tellurium and probably also in polonium. In addition, there is very strong evidence that the radio-active lead obtained by Hofmann contains the three products radium D, E and F together. The changes of radium as far as they are at present known, are shown diagrammatically in Fig. 95. It is possible that further investigation will show that the transformation does not end with radium F. [Illustration: Fig. 95.] While we have shown that radium D is the parent of E, we have not given any conclusive evidence that E is the parent of F. This evidence is, however, supplied by the following experiment. A platinum plate, made active in the manner already described, was placed in an electric furnace and heated for four minutes at about 1000° C. Most of the products D and F were volatilized, but E was left behind. Since the parent matter D was removed, E at once commenced to lose its β ray activity. At the same time it was observed that the small α ray activity, left behind on the platinum plate, increased rapidly at first and then more slowly, as the activity of E became smaller and smaller. This experiment shows conclusively that E was the parent of F, the α ray product.