IX, A. 1 



Wright and Smith: Radium Emanation 



59 



Table I shows that in every case the emanation obtained from 

 bubbling air through the cold solution is considerably less than 

 that obtained from the boiling solution. The table is divided 

 into 5 series according to the conditions existing during the 

 tests. Series I, III, and IV were made on a solution contain- 

 ing 3.14 X 10'^ gram of radium, series II and V on a solution 

 containing 6.28 X 10"^" gram. The conditions of the tests in 

 series II and V were identical with those existing throughout the 

 greater part of the work on the radium-emanation content of 

 the air; therefore, the ratio of the mean of series II to that of 

 series V will be used as a reduction factor in our final calcu- 

 lations of the radium emanation in the atmosphere. This ratio 

 is equal to 0,792. 



TESTS ON THE SECOND POINT 



Since Satterly found that charcoal showed signs of saturation 

 especially for tests extending over several hours, it was deemed 

 advisable to determine whether under the conditions of our 

 experiments evidence of saturation existed. Tests were first 

 made by putting several of the electrosilica tubes which we were 

 using in series. The results are shown in Table II. 



Table II. — Efficiency of coconut charcoal a^ an absorber of radium 



emanation. 



Date. 



Strength 

 of solu- 

 tion. 

 Grams 



X109. 



in series. 



ElectroBC 



Tube 

 No.l. 



ope readin 



Tube 

 No. 2. 



g less nat 



Tube 

 No. 3. 



ural leak. 



Tube 

 No. 4. 



Oct. 14,1912 

 Oct. 17, 1912 



3.14 

 3. 14 



Hrs. 



4 4 ! 0.831 

 3 4 ■ 0-9.«!ii 



0.003 

 0.048 



0.002 

 0.002 



0.003 















The emanation in this case is apparently all absorbed in the 

 first two tubes, the electroscope reading for the third and fourth 

 being so small as to be easily within the limits of observational 

 error, the natural leak having a mean value of 0.022. In Table 

 III are given the results of a series of observations in which 

 2 tubes were placed in series and the duration of the tests varied 

 from five to twenty hours. Although not so conclusive as the 

 results of Table II, all evidence of saturation is lacking. 



