Weights of Radium and Thorium Emanations. 67 



It is the values of 1 7T7T < / /o anc ^ I !/— TTW/o ) which are tabulated 



in the columns headed y and u respectively (Tables III., IV., 

 and V.). 



For carbon dioxide and sulphur dioxide V and i/ are the 

 same volumes. 



In the experiments with the emanation y and y were 

 determined electrically as described above. The values of y, 

 given in the tables, have been corrected for the natural 

 decay of the emanation in the interval during which diffusion 

 was taking place. From the results of Rutherford and 

 Soddy (Phil. Mag. April 1903) the activity of the emanation 

 falls to half its value in 3*71 days; the mean of y and y was 

 taken, and the loss of activity of this quantity in the time t 

 calculated and added to the observed value of //. To make 

 the method of calculation clear, one of the observations 

 taken with plug I. is given in full : — 



Time 

 10.16 a.m. . . Sensitiveness of electrometer in scale-divisions per volt, 86. 

 Diffusion-vessel filled to 67*8 c. c. 



10.27 a.m. .. 343 c. c. carried into testing-vessel, leaving 33 - o c.c. in 



the diffusion-vessel. 



10.28 a.m. . . Deflexion of electrometer-needle in 20 seconds, corrected 



for lack of uniformity of scale, 224. 

 12.33 p.m. . . Sensitiveness of electrometer in scale-divisions per volt, 82. 



Volume of gas in diffusion-vessel 33*7 c. c. 

 12.41 p.m. . . 27*7 c. c. carried into testing-vessel. 

 12*42 p.m. . . Deflexion of electrometer-needle in 20 seconds, corrected 



for lack of uniformity of scale, 105. 

 Deflexion corrected to 86 scale-divisions per volt, and 



to volume 34*3 c. c. carried into testing-vessel 



irr 86 34-3 lqr . 

 = 10oX 82 X 2T7 = 136 - 



Corrected for natural decay of emanation, 139. 



Time during which diffusion had been proceeding, 134 minutes. 



. 33-6 , 224 .™ 



X = 134x-4343 l0 ^139 =12a 



In the last column of Table III. are tabulated the values of 

 X^/M, in which M is the molecular weight of the gas 

 employed. In Tables IV. and V., however, the values of 

 X obtained are first multiplied respectively by '1362 and 

 *312 to reduce them to equality with the corresponding 

 quantities for plug I., and the values of *1362\v/M and 



•312X\/M respectively tabulated in the last columns. This 



F2 



