Manchester ATeiuoirs, Vol. /Hi. (1909), No. 1. 



VII. The Volatility of Radium A and Radium C. 

 By Walter Makower, B.A., B.Sc. 



[Received and read December ijth, igo8.) 



In the course of some experiments it was found 

 necessary to know the temperature at which radium A 

 volatilised, and as this had not previously been deter- 

 mined with accuracy, a series of experiments was carried 

 out to determine the volatilisation point of this product. 

 It was also considered of interest to redetermine the 

 temperature of volatilisation of radium C under different 

 conditions to see whether its volatility depended on its 

 environment. The experiment on this point will be 

 recorded after those relating to the volatility of radium A 

 have been described and discussed. 



The Volatility of Radium A. 



The method used to determine the volatilisation point 

 of radium A consisted in exposing a nickel rod to a 

 known quantity of radium emanation for ten minutes at 

 different temperatures, and examining the nature of the 

 deposit so collected on the rod by observing the activity 

 of the wire, measured by the a rays, and its rate of decay 

 after removal from the emanation by means of a quadrant 

 electrometer. Under these circumstances at ordinary 

 temperatures there is a rapid decay of activity after 

 removing the rod from the emanation for about fifteen 

 minutes, after which the activity becomes constant for 

 nearly half-an-hour, when it again begins to fall off 

 slowly. As is well known, the initial rapid fall of activity 



January i^ih, zgog. 



