the Origin of Radium. 



601 



gram of the substance. A series of experiments showed that 

 this factor could be more quickly and equally accurately 

 determined by sealing up the sample for a definite period of 

 about four days, measuring the activity of the emanation 

 which then accumulated, and calculating the maximum value 

 by the equation 



where L was the value of the activity measured. 



The arrangement of the apparatus used for the separation 

 and collection of the radium emanation contained in the 

 various samples is shown in the accompanying diagram. 

 The flask A was about half full of boiled water and was 

 closed with a rubber stopper, through which passed a glass 



tube extending to b. This tube had a branch at a, to which 



attached a short section of rubber tubing and a screw 



pinchcock. The Mask E contained a dilute, boiling solution 



of sodium hydroxide (1. per cent.), a portion of which at the 



ining of the operation was displaced to fill the burette 



o£ the powdered sample was weighed out into 



* For farther details concerning the manipulation of this apparatus 

 Liner. Journ. of Seience, xviii. p. 380 (1004). 



Phil Mag. 8. 6. Vol. 9. Xo. 52. April 1905. 2 R 



