482 Dr. Harry C. Jones on the 



potassium sulphate, barium chloride, magnesium sulphate, 

 zinc chloride, sulphuric and phosphoric acids, and potassium 

 and sodium carbonates. The comparison will only be carried 

 to 0*002 or 0*003 molec. normal, beyond which the error in 

 my results is necessarily large, from the very small lowering 

 of the freezing-point to be measured. 



Since the following comparison is only approximate, and 

 does not demand the greatest accuracy, the highest molecular 

 conductivity found will be taken as yu,x> in the calculation — 



dissociation = -^— . 



The results from the two methods are given in the Table on 

 the opposite page, where column 1 contains the names of the 

 compounds investigated, with the values used as /jlzo ; 2, con- 

 centrations of solutions compared, in gram-molecular normal ; 

 3, the dissociation as calculated from Kohlrausch's results, 

 using Conductivity method ; 4, the dissociation calculated 

 from my results, using the improved Freezing-point 

 method. 



The general agreement between the results from the two 

 methods is unmistakable. Indeed, it is as close as could be 

 expected when it is considered that such widely different 

 properties of the ions as the lowering of the freezing-point 

 of the solvent and the conduction of electricity are utilized 

 in the two cases. Again, each method is doubtless affected 

 by small errors peculiar to itself. It has been pointed 

 out that a slight difference in the amount of dissociation 

 would be produced by the difference in temperature at which 

 the two series of measurements were inade*. 



The dissociation of some of the salts as calculated from the 

 lowering of the freezing-point is slightly greater than that 

 calculated from the " Conductivity." A possible explanation 

 in the case of the carbonates is to be found in the hydrolysis 

 produced by the water. Shields f has shown that the amount 

 of hydrolysis is at least nearly proportional to the square root of 

 the dilution. The products of the hydrolysis would conduct 

 better than the carbonate molecules, and fjuco at the greater 

 dilution would be too large relative to (jlv. This would give 

 too little dissociation from the conductivity results for 

 those concentrations where the results are compared. This 

 would also explain why the difference increases with the con- 

 centration. The dissociation of magnesium sulphate, as 

 calculated from the freezing-point results, is considerably 

 lower for the concentrated solutions. This has been explained 



* Jones, Ber. d. deutsch. Chem. Gesell. xxvi. p. 550. 

 t Shields, Phil, Mag. [5] xxxv. p. 377. 



