?j# Conductivity of Aqueous Solutions. Part XII. 



by a graphical method (see section 17, page 50) which involved no 

 assumption in regard to the value of A , this being regarded as a third 

 constant to be determined from the data themselves. In general, the value 

 of n could be found within 0.02 or 0.03 units. 



It is evident that, if the conductance-ratio A/A can be taken as a meas- 

 ure of the ionization (y), the latter changes with the concentration in the 

 case of all these substances in accordance with an entirely similar expo- 



( C- \ ' 

 nential law, namely, in accordance with the function n -y~ = const.. 



<- ( 1 7 ; 



in which n has values varying with different substances only between 1.40 

 and 1.55. 



In a previous article* emphasis was laid on the remarkable fact that 

 at ordinary temperature the form of the functional relation between ioni- 

 zation and concentration is the same for salts of different ionic types. 

 These results show that this is also true at high temperatures, and, more- 

 over, that even the very large variation of temperature here involved and 

 the large consequent change in the character of the solvent affect only 

 slightly, if at all, the value of the exponent in this purely empirical rela- 

 tion. Thus an additional confirmation is given to the important conclu- 

 sion that the form of the concentration-function is independent of the 

 number of ions into which the salt dissociates. This seems to show almost 

 conclusively that chemical mass-action has no appreciable influence in 

 determining the equilibrium between the ions and the un-ionized part of 

 largely dissociated substances. How complete this contradiction with the 

 mass-action law is, is seen when it is recalled that for di-ionic and tri-ionic 

 salts this law requires that the concentration of the un-ionized substance 

 be proportional to the square and cube, respectively, of the concentration 

 of the ions, while the experimental data show that it is proportional to the 

 f power of that concentration, whatever may be the type of salt. 



It has also been shown in the preceding articles (pages 49 and 139) 

 that the functions A A = KC* and A A = K(C\y, which contain 

 only two arbitrary constants (A and K) satisfactorily express the results 

 with potassium chloride, sodium chloride, hydrochloric acid, and sodium 

 hydroxide at any rate up to 218 between the concentrations of 0.1 and 

 0.002 or 0.0005 normal. Since, however, the data at still smaller concen- 

 trations, as determined by Kohlrausch and others at 18, do not conform 

 to the requirements of these functions, they apparently do not give by 

 extrapolation a correct value of A , and correspondingly the ratio A/A 



*Noyes, The Physical Properties of Aqueous Salt Solutions in Relation to the 

 Ionic Theory, Congress of Arts and Science, St. Louis Exposition, 4, 317 (1904) ; 

 Technology Quarterly, 17, 300 (1904) ; Science, 20, 582 (1904) ; abstract in Z. phys. 

 Chem., 52, 635. 



