DECOMPOSITIOy OE HYDRIODIC ACID. — CREIGHTON. 



13 



The curves for these numbers are similar in form to those 

 for 24°C. The only difference between the behaviour at this 

 temperature and that at 24°C. is that at the former the decom- 

 position of the solution is much slower, and the equilibrium 

 vajues consequently much longer in being reached. The effect 

 of radium is again apparently only to increase the action in 

 degree, but not to change it in type. Here, too, as at 24*^0., 

 there is probably no third product being formed from the iodine. 

 The reaction was next observed at 86°C., and the following 

 table shows the results obtained : 



Table V. 





No. of cc. of ,^^ Na2 S, 0, 



12o0 ^ ~ .J 



solution required in titration 





when the decomposition of hydriodic acid solution takes 





place in the presence of 





Time in 







hours. 



No raxlium 



Radium 





Observed 



Calculated from 

 y = a (l-e-") 



Observed 



Calculated from 

 y = a (e"*"— e"*^^' ) 

 a = 3 3, 6-0.0«, 





y 



a = 92.b = 70 



y 



c = 0.3l 



0.5 



0.18 



0.27 



0.30 



0.38 



1 



0.35 



0.46 



0.60 



0.69 



2 



70 



0.69 



1.15 



1.15 



3 



0.85 



0.81 



1.50 



1.46 



4 



0.88 



0.87 



1.65 



1.64 



6 



0.93 



0.91 



1.75 



1.79 



8 



0.92 



0.92 



1.75 



1.75 



10 



0.93 



0.92 



1.65 



1.64 



12 



0.91 



0.92 



1.50 



1.52 



16 



0.90 



0.92 



1.25 



1.24 



27 



0.93 



0.92 



0.65 



0.65 



The curves formed from these numbers are given in figure 2. 



