The Boiling Point of the Radium Emanation

Abstract

IT was shown by Rutherford and Soddy in 1903 that the radium emanation was condensed from the gases with which it was mixed at a temperature of about -150° C. From observations of the range of temperature of condensation and volatilisation it was concluded that the condensed emanation exerted a sensible vapour pressure. This has been confirmed by later experiments, using much Varger quantities of emanation. Sir William Ramsay and Cameron have pointed out that the emanation, condensed in a glass tube kept at the temperature of liquid air, can be removed by continuous pumping, thus indicating appreciable vapour pressure even at that low temperature. I have found that the rate of removal of the emanation in this way increases rapidly as the temperature of complete volatilisation is approached.