Polymerization in Cadmium Iodide Sohitions. 463 



third column are the observed freezing point depressions, which 

 in nearly every case are the mean of two or three separate 

 determinations. The fourth and fifth columns contain the 

 observed values, for the pure cadmium iodide solution, of the 

 van't Hoff coefficients, and of the apparent degree of ioniza- 

 tion 7, as calculated in the ordinary way from i. 









Table IV. 















i = 



i—1 



Dep. 



Molec. 



(Cdls) 



Dissolved 



F. p. 



van't Hoff 



y = ~ir 



due to 



dep. for 





iodine 



dep. 



coeff. 



2 



iodine 



iodine 



500 



0-0 



1-067° 



1-147 



7-35^ 







a 



9-4 



1-089 







0-022° 



2-34(?) 



a 



19-6 



1-095 







0-028 



1-43 



u 



279 



1-112 







0-045 



1-61 



(( 



*40-4 



1-125 







0-058 



1-44 



250 



0-0 



0-533° 



1-145 



7-25^ 







u 



9-33 



0-546 







0-013° 



1-40 



a 



19-4 



0-558 







0-025 



1-29 



<( 



24-9 



0-5G7 







0-034 



1-37 



(( 



*33-6 



0-579 







0-046 



1-37 



125 



0-0 



0-277° 



1-193 



9-65^ 







a 



5-93 



0-285 







0-008° 



1-35 



a 



10-29 



0-293 







0-016 



1-56 



« 



16-75 



0-301 







0-024 



1-43 



iC 



*27-5 



0-317 







0-040 



1-46 



10 



0-0 



0-0365° 



1-962 



48-1^ 







« 



2-344 



0-0394 







0-0029° 



1-24 



a 



4-266 



0-0424 







0-0059 



1-38 



u 



*7-53 



0-0453 







0-0088 



117 



Previous determinations of i for cadmium iodide by the 

 freezing point method have been made by Arrhenius,* by H. 

 C. JoneSjt and by Chambers and Frazer.:j: Our values at the 

 two lowest concentrations are in excellent agreement with those 

 of Jones (whose results only cover concentrations up to O'l 

 molar) and at the two higher concentrations they are close to 

 the mean between the results of Arrhenius and those of Cham- 

 bers and Frazer. No explanation is offered for the fact that i 

 is slightly larger in 0-5 molar cadmium iodide than in the 0*25 

 molar solution, but the effect is real as it is even more evident 

 in the results of the other investigators than in our own. 

 Chambers and Frazer ascribe the phenomenon to hydration. 



The last column of Table Y shows the " molecular depres- 

 sion for iodine " as obtained by dividing the depression due to 

 iodine (column six) by its total concentration as given in col- 



*Zeitsclir. phys. Chem., ii, 491, 1888. 



+ Ibid., xi, 544, 1893. 



i Am. Chem. Jour., xxiii, 512, 1900. 



