Emanation in the Lower Regions of the Atmosphere. 29 

 Table XI. — Lone Runs. 





Dura- 

 tion of 

 expo- 

 sure. 



Air alone. 



Air plus Sol 



ution. 







Date 

 1909. 



Oct. 26 -27. 



Tube. 



Vol. of 

 air. 



Emana- 

 tion 

 caught. 



Tube. 



Vol. of 

 air. 



Emana- 

 tion 

 caught. 



caught from 

 the Solution. 



equivalent 

 of the Air. '■ 



hrs. 

 22* 



A 



630 



11 \ 



B 



660 



4, 



4-7-12=3-5 



52xl0" 12 i 



„ 27-28. 



21 



B 



610 



•9 



A 



640 



4-1 



4-1- -8 = 33 



—19 



37x10 ' 



Nov. 2-3... 



21 



B 



650 



22 



A 



650 



52 



5-2-2-0=3-2 



88x10" 12 



„ 3-4... 



21 



A 



640 



26 



B 



635 



67 



67-2-9=3-8 



-12 



109x10 



To calculate the mean emanation content of the air for the 



months March-August we use the mean values 2*45 for the 



average value of the emanation from 630 litres of air, and 



3*45 for the amount of emanation absorbed from a solution 



3'14xl0~ 9 

 containing ^ gm. of radium in 21 hours. 



Therefore the average radium-equivalent of the air 



_1000 2j45 3-14 xlO- 9 

 ~ 630 X 3-45 X 5 



= 105xl0- 12 gm. 



The lowest value is about 35 xlO -12 p. and the highest 

 value about 350 x 10 -12 gin. 



Discussion of the results of experiments made on the variation 

 of the amount of radium emanation in the air with weather 

 conditions. 



The only other experiments besides the author's on the 

 measurement of the amount of radium emanation in the air 

 and its association with meteorological phenomena are those 

 of Eve * made at Montreal. The method was the same, but 

 Eve's exposures lasted 2*7 days, whereas mine lasted only 

 21 hours. Eve found that the ratio of the greatest to the 

 least values was 7:1. 1 get 10 : 1. He found also that 

 the amounts in summer and winter were not widely different; 

 this also agrees with my results. 



Eve also found that the approach of a deep cyclone, ac- 

 companied by heavy rain or a quick fall of snow, causes an 



* Phil. Macr. Oct. 1908. 



