﻿348 



Mr. A. Fleck on tlie Condensation of 



Results. — Fig. 6 shows the curves obtained ; all values 

 were worked out by the same methods, but the points marked 



Fig. 6. 



-60 -go '100' -/20" -/*0° -/60° -l%0" 



Kadium emanation in exhausted two-limb tube (fig. 5). 



with circles were obtained between March 20th and 26th and 

 those with crosses between the 26th and the 28th of the same 

 month. It will be seen that they lie on two curves, one of 

 which crosses the other. 



With reference to curve A, it will be noticed that here 

 again there is evidence of a maximum point about —80° C, 

 but that there is no trace of the maximum previously 

 obtained at —161° C. In view of the comparatively large 

 variation of the points between —100° C. and —150° C., it is 

 not w r ise to attach any value to the apparent change of slope 

 at —160° C. It will be noticed also that the curve in the 

 neighbourhood of the maximum is much less steep in this 

 case than in the case of the maximum at —72° C. in curve 

 D (fig. 4). This and also the absence of the maximum at 

 — 161° C. may be due to the fact that in this experiment 

 there is always a slow gradient of temperature owing to the 

 upward current of air in the wide tube, whereas in the 

 previous experiments, where pentane was used, the change 

 from the low temperature to that of the room was very quick. 



The second curve was obtained in the course of attempts 

 to add more points and to verify those already obtained. 



