340 PROPERTIES OF ELECTRICALLY CONDUCTING SYSTEMS 



where A, B and K are constants and C u and C^ are the concentrations of 



the ions and the un-ionized molecules, respectively. For binary electro- 

 lytes A has a value of approximately 1.5, B of 0.3 and K of 1.0. Applied 

 to aqueous solutions of sodium and potassium chlorides, this equation 

 was found to reproduce the results quite closely up to 0.05 N, the con- 

 stants of the equation being fitted to the experimental values. Similar 

 results were obtained with a number of ternary salts. The equation is 

 not applicable to solutions in solvents of lower dielectric constant such as 

 ammonia, even at low concentrations. At high concentrations, in sol- 

 vents of dielectric constant less than 20, it is obviously inapplicable, 

 since, according to this equation, A necessarily increases with concentra- 

 tion. It may be noted that the form of this equation resembles somewhat 

 that of Bronsted's for the solubility of a salt in the presence of other 

 salts. 



b. Theory of Ghosh. The most comprehensive theory which has 

 been proposed to account for the behavior of solutions of electrolytes is 

 that of Ghosh. 20 Ghosh assumes that strong electrolytes are completely 

 ionized, but that only those ions whose energy is sufficiently great to over- 

 come the electrostatic field due to the charges are active in carrying the 

 current. It is difficult to see how Ghosh's activity coefficient differs from 

 the usual ionization coefficient. Apparently, what this author has in 

 mind is that the ionic complexes persist in the neutral molecules. While 

 such an assumption is not fundamental to the older ionic theory, it is 

 nevertheless true that previous investigators 21 in this field have long 

 since recognized that in the neutral molecule the identity of the ionic 

 complexes is not lost. The theory of Ghosh, as well as those of some 

 other writers, would be more readily understandable to most readers if 

 the customary nomenclature had been retained. 



Ghosh calculates the potential due to the field on the assumption that 

 the ions are distributed in the medium in a definite manner forming a 

 space lattice. He assumes that the space lattice of a salt in solution 

 corresponds to that of the salt in the crystalline state and therefrom cal- 

 culates the distance between the positive and negative charges. In 

 calculating the potential, Ghosh assumes that the ions form doublets so 

 that the work involved in separating the ions is due only to the N pairs 

 of positive and negative ions. This theory has been criticized by Part- 

 ington, 22 Chapman and George, 23 and more recently by Kraus. 24 These 



20 Ghosh, Trans. Chem. Soc. 113, 449, 627, 707, 790 (1918). 



21 Noyes, Aqueous Solutions at High Temperatures, Carnegie Publication No, 63, p. 350 

 (1907) . 



22 Partington, Trans. Faraday Soc. 15, 111 (1919-20). 



23 Chapman and George, Phil. Mag. 41, 799 (1921). 



"Kraus, J. Am. Chem. Soc. W, Dec., 1921. ..... . . , 



