33 211 



Measurements of the ionisation: 



Hence we get, by means of the curve, the values of : 



\nl 



showing an average of 86.9 = a'„,. 



The density of the air at 746 mm. and 6° C. is d - 0,001242. The corrected 

 value of a,„ is therefore 



a„, = 86.9 (l +0.215^-^*^^21^^^^) = ^^'^^ 



The amount of emanation in question is thus 



E = 86.5 X 1.347 = 116.5 



while the reduced volume of the spring gas investigated is 



_ 102.2 _ 736 _ 



1+0 00367x11 760 «o-^ ccm. 



The spring gas contains therefore at the time of examination, an amount of 

 emanation which is expressed by : — 



Q = ^ = 1.225. 



Multiplying 1.225 by eS.icxio "(^ / being 12600 seconds, we obtain the amount 

 of emanation contained in 1 ccm. of the spring gas at tbe time of collection. 

 Therefore 



Ci = 1.225 X e2 16 ><)o-«K 12600 = i.26 per gr. uranium per second. 



I). K. l>. VUlensk. Selsk. Skr.. 7. li«kkc, niiluiviclensk oU inalheiii Af.l. VIII. 4. 28 



