54 Conductivity of Aqueous Solutions. Part II. 



suffice to recall that the results with the two salts are satisfactorily 

 expressed up to 156 (except at very low concentrations) by the functions 

 (1 y) =KC i and (1 y) = K{Cy) 1 , where y is the conductai ice-ratio 

 A/A or the ionization; and also that when the function C(l y) = 

 K(Cy) n is applied to the data the value of the exponent n varies at 

 different temperatures only from 1.40 to 1.50 in the case of either of 

 the salts. It is worthy of note that the last function may also be written 



in the form: , y } - = K{Cy) m where m, which is equal to 2 n, has 

 C (1 y) 



values between 0.50 and 0.60. 



It will be seen that, especially in the 80 milli-normal solution, the ioni- 

 zation has decreased very greatly at the higher temperatures, namely, 

 from 86 - 87 per cent at 18 to 63 - 64 per cent at 306 ; and that the 

 decrease is becoming extremely rapid at those temperatures. 



Table 12 also shows that the ionization values for the two chlorides are 

 nearly identical at all temperatures and concentrations, the variations 

 being irregular and sometimes in opposite directions. 



20. SUMMARY. 



In this article has been described the construction of a platinum-lined 

 bomb of 124 c.cm. capacity with electrodes insulated by quartz-crystal 

 cylinders, by means of which the conductivity and specific volume of 

 aqueous salt solutions can be determined with an accuracy of 0.2 or 0.3 

 per cent, at least up to a temperature of 306. 



Measurements of the conductivity and specific volume have been made 

 upon solutions of sodium and potassium chlorides at concentrations vary- 

 ing from 0.0005 to 0.1 normal, at the temperatures 100, 140, 156, 218, 

 281, and 306. Conductance values for potassium chloride at tempera- 

 tures intermediate between 18 and 100 have also been presented. For 

 the final results see table 9, page 47. 



The results obtained with these salts show that even at the highest 

 temperature the ionization calculated from the conductance-ratio does not 

 change with the concentration in much closer accord with the require- 

 ment of the mass-action law than at the ordinary temperature. Vari- 

 ous empirical functions which have been proposed for the expression of 

 the change of conductance with the concentration were tested as to their 

 applicability to the results at these widely different temperatures by a 

 graphical method by which the effect of the uncertainty in the equivalent 

 conductance (A ) for zero concentration was eliminated. It was 

 found that of those containing only two arbitrary constants the ones 

 given by Kohlrausch, A A = KC l , and by Barmwater, A A = 

 KA*C l , were satisfactory at temperatures up to 156, but that at higher 



