PROPERTIES OF AQUEOUS SALT SOLUTIONS 317 



to this function are per cent in the case of ten uni-univalent salts, 

 $ per cent in the case of nine uni-bivalent salts, and also J per cent 

 in the case of three uni-tri- and uni-quadrivalent salts. The maximum 

 deviations are two or three times as great. It is of interest to note 

 that the strong mineral acids, hydrochloric and nitric, behave like 

 salts in this respect. These functions have been shown to apply to 

 potassium and sodium chlorides through a range of temperature 

 extending from 18 to 306. They do not apply at all closely to 

 such salts of the bi-bivalent type as magnesium and copper sulphates, 

 perhaps owing to appreciable hydrolysis. Nor do they represent 

 satisfactorily the experimental data for any kind of salts at the very 

 low concentrations lying between J-Q^-Q-Q and ^^g-"5" normal, nor at 

 concentrations higher than ^ normal. 



The experimental results are also well expressed by the statement 

 that in the case both of uni-univalent and uni-bivalent salts, between the 

 concentrations of y^ J-Q^ and 4- normal, the concentration of the un- 

 ionized molecules is proportional to the concentration of the ions raised to 

 a constant power, varying somewhat with the salt and the temperature, 

 but as a rule only between the limits of 1.43 and 1.56. That is, c (1 -jr) 

 K(cr) n , where n >1.43 and < 1.56. 



This general function was first applied by Storch and was afterward 

 further discussed by Euler and Bancroft. It has the advantage over 

 the previous ones that it represents the data with accuracy even up 

 to the highest dilutions, and therefore can be used for obtaining the 

 limiting conductivity at zero concentration. 



The applicability to the salts of different types of either of these 

 principles governing the change of ionization with the concentration 

 leads to the important conclusion that the form of the concentration 

 function is independent of the number of ions into which the mole- 

 cules of the salt dissociate. This remarkable fact, though previously 

 recognized, has not been sufficiently emphasized, and it has been 

 often ignored in discussions of the cause of the deviation of the ioniza- 

 tion of salts from the requirements of the Mass- Action Law. It seems 

 to me to show almost conclusively that chemical mass-action has no 

 appreciable influence in determining the equilibrium between ions and 

 un-ionized molecules. How complete the contradiction with the Mass- 

 Action Law is may be illustrated by citing the specific facts that for 

 di-ionic, tri-ionic, and tetra-ionic salts this law requires that the con- 

 centration of the un-ionized molecules be proportional to the square, 

 the cube, and the fourth power, respectively, of the concentration of 

 the ions; while the experimental data show that it is approximately 

 proportional to the -| power of that concentration, whatever may be 

 the type of salt. 



Having seen in what manner the degree of ionization varies when 

 the concentrations of both ions of the salt are simultaneouslv varied 



