ABSTRACT
This chapter describes that the radioactive emanation from thorium compounds passed in unchanged amount through a tube cooled to 78 with solid carbon dioxide and ether. The acquisition of a liquid air plant has enabled the authors to repeat the experiment at a lower temperature, with the result that they have now succeeded in condensing both the thorium and the radium emanations. No trace of emanation escaped in the issuing gas either in the case of radium or of thorium. The radium or thorium compound was then removed, and the gas current sent directly through the spiral tube, which was quickly taken out of the liquid air and placed in cotton wool. The exact temperatures cannot yet be given, but as a first approximation it may be said that for the radium emanation the volatilisation point lies in the neighbourhood of 130 and for the thorium emanation about five degrees lower.
