Activity of freshly-formed Radium Emanation. 717 



The following is a typical set of results arranged in order. 

 A is the average ionization current for about ten minutes 

 through one testing vessel in scale divisions per minute, 

 B that for the other vessel : the third column shows the 

 order of sequence of the vessels as regards the air current. 



A B 



3*63 AB 



3-59 



3-76 



(3-24) 

 3-41 

 3-98 



3-60 

 (3*47) BA 



3-40 

 3*77 



The figures in brackets should, perhaps, be disregarded, as 



they were obtained very shortly after the reversal and so 



might be affected by irregularities due to the temporary 



stoppage of the emanation current through the vessels during 



the changing- of the connexions. Taking means of the 



remaining figures, and subtracting the natural activities of 



the vessels, which were 0*51 for A and 0*44 for B, we obtain: — 



A B 



3-18 3*15 AB 



3-18 3-14 BA 



As these figures are only the means of the above results, 

 which involve such large variations, little stress can be laid 

 on their remarkable agreement beyond the fact that they 

 show that it is improbable that the variation between the 

 activities of the emanation in the first and second vessels 

 exceeds 5 per cent., as such a difference would probably have 

 been noticeable. Other determinations gave similar results : 

 irregular fluctuations always occurred, the ionization currents 

 sometimes increasing and sometimes decreasing, but the mean 

 for the first and second vessels was always nearly the same. 



In the determination to which the above figures apply the 

 age of the emanation entering the first vessel was estimated 



n © 



at about 5 seconds on the hypothesis that no time was wasted 

 in deemanation ; the time required to traverse the vessel 

 was about 9 seconds, making the average age of the emanation 

 in the first vessel about 10 seconds. The age of the emanation 

 in the second vessel was 5 minutes. 



Other determinations were made with less rapid air 

 Phil. Mag. S. 6. Vol/27. No. 160. April 1914. 3 B 



