786 Mr. J. Satterly on the Absorption of 



The results are represented in fig. 2, and it is clearly 

 shown that the charcoal in the first tube (B) approaches 

 saturation when the exposure is long and the amount of 

 emanation sent along the tube is high. 



V. 



Percentage of Emanation absorbed by Coconut Charcoal. 



It is o£ interest to find what percentage of the emanation 

 given off by a radium solution is absorbed by the charcoal 

 under the conditions of my experiments. 



Using a solution containing | of 1*57 x 10~ 9 gm.* radium, 

 six experiments were made with the silica tubes containing 

 the coconut charcoal arranged as shown below : — 



, Tube A or B Gauge Ay 



Out,r_ / . V _ 



air. \ / 



NRadium Solution — Tube B or A — Gauge W l ump ' 



The air-streams were adjusted to '48 litre per minute 

 through each branch, and the exposure was continued for 

 exactly 21 hours. Subtracting the amount of emanation 

 caught in the tube in the "air alone r ' arm from the amount 

 caught in the tube in the other arm, wo get the amount 

 caught by the charcoal from the solution. 



Before beginning this set of experiments the tubes had 

 been emptied and made up afresh with 130 gms. of charcoal 

 in each, so that the results are not absolutely comparable 

 with earlier results. 



The results were : — 



Tube A 5-1 4-5 4*9 Mean 4"«, 



TubeB 4-1 4-5 4-1 „ 4*2, 



the amounts being expressed in terms of the leaks produced 

 in the testing vessel expressed in cms. per minute of my 

 electrometer scale, and reduced to a common sensitiveness 

 (90 divisions per volt). 



It now remained to find the total amount of emanation 

 produced by the same solution in 21 hours. To do this the 

 bottle B containing the solution was connected up to a 

 condenser C and heated in a brine bath (b.p. 105° C), as 



* This was a portion of a fresh radium solution kindly supplied to the 

 author by Professor Rutherford. 



