Relation between L 



ramum an 



d Radiu 



m. 



213 



and the ratio of radium to uranium required to make the 

 results agree with those from uranium minerals was 

 3-4 Xl0" 7 . 



Calibration of Electroscojje. 



I. Old Instrument. 



Standard. 



Uranium 

 (nigs.). 



-r, v T , Constant 



Kadium Leak , fl) , , /in 19 



/ /,. (grms. ot KaX 1U — 1<* 

 (gnus. (divs. per ^ 

 W ? A 1n v . ' required to give 

 X 10- 1U) minute). , 1- • v 

 .1 div. per nun.). 



Joachimstahl pitchblende ... 



(new standard) 

 Joachimstahl pitchblende ... 



(old standard J. P. B.) 



0-4397 

 0-3539 



1-495 j 2803 5-33 

 1-203 ' 22-40 537 



Mean 



5*35 



II. New Instrument. 



Mean 



1446 



On April 23, 1915, the tip of the leaf of the electroscope 

 was broken off through an accident. The instrument with 

 its shortened leaf was reealibrated. 



Standard. 



Uranium 

 (mgs.). 



Radium 



(grins. 



X 10-10) 



Leak 

 (divs. per 

 minute). 



Constant. 



Joachimstahl pitchblende 1 . 

 Joachimstahl pitchblende 2 . 

 Radium-barium carbonate 1 . 

 Cornish pitchblende 2 



03366 



0-5388 



03620 



1144 

 1-832 

 3-993 

 12310 

 13-463 



7-22 

 11-65 



2510 

 8 04 



15-72 

 1590 



15-53 



Radium-barium chloride 2 ... 



Mean ... 



15-66 



