12 



THE INFLUENCE OF RADIUM ON THE 

 Table III. 



Time in 

 hours. 



No radium curve .n— 1 54 



Radium curve .?(. = 2. 10 



\ i^ X' o .-» Rate of 



y 1 



Amt. Nav Ss O3 



y 



Rate of 



change. 



A 



2 

 3 



5 



7 

 10 



0.45 

 0.65 

 0.92 



1.10 ■ 



1.23 



0.173 

 0.183 

 0.182 

 0.719 

 0.160 



0.58 

 0.85 

 1.25 

 1.51 

 1.73 



0.162 

 0.173 

 0.181 

 0.181 

 0.174 



This justifies us in supposing that at 24''C., both with and 

 without radium, there is no third product being formed from 

 the iodine ; and the numbers given in columns three and five of 

 Table II were calculated from ecjuation (2). As was pointed 

 out before, the action of radium serves merely to accelerate 

 the action which goes on in its absence. 



In order to see if more light would be thrown on the action 

 of the radium the decomposition of hydriodic acid was observed 

 at other temperatures. 



The reaction was next observed at 12°C., and the results 

 are given in the following table : 



Table IV. 



No. of cc. of .-^ Nag S2 O3 solution required in titration 

 when the decomposition of hydriodic acid takes place in 

 the dark in the presence of 



Time in 

 hours. 



No radium. 



Observed 



Calculated from 



y = a d-e-'") 

 a = \ 92,6 = 0.07 



Radium 



Observed 



Calculated from 



y = a (l-e-*") 

 a = 2.90,/> = 0.07 



2.5 



0.30 



0.31 



0.49 



0.46 



8.0 



0.75 



0.83 



1.15 



1.25 



10.0 



0.95 



0.96 



1.43 



1.46 



18.0 



1.47 



1.37 



2.15 



2.08 



30.0 



1.69 



1.69 



2.55 



2.55 



