CARRIERS IN ELECTROLYTIC SOLUTIONS 199 



is, if this is the true transference number of the anion, and if T^ is the 



true transference number of the cation, then according to Washburn 2 

 the net transfer of water per equivalent of electricity passing through 

 the solution will be: 



(47) 



V IA/ V 14/ <A/ 



where JV is the net transfer of water per equivalent of electricity. 

 In general, therefore, the passage of a current through a solution will 



E 



be accompanied by a net transfer of water, whose value is N per 



equivalent of electricity. This transfer of water may be determined by 

 introducing into the solution a substance which itself takes no part in 

 the transfer of the charge. The change in the concentration of the water 

 with respect to this reference substance will give the transfer of water, 

 and the change in the concentration of the salt with respect to the same 

 reference substance will give the true transference number of the salt at 

 the same time. It follows, therefore, that if the true transference num- 

 ber of the salt and the net transference number of the water are known, 

 the relative amounts of water associated with the two ions may be deter- 

 mined. As ordinarily carried out, transference experiments in which 

 water is employed as reference substance yield, not the true transference 

 number, but a transference number differing therefrom by an amount 

 depending upon the relative amount of water transferred. The relation 

 between the true and the ordinary transference number is given by the 

 equation: 



(48) 



N 



where T^ is the ordinary transference number of the cation and -^ 



w 



is the ratio of the number of mols of salt to that of water in the solution. 

 If transference measurements on various electrolytes with a common ion 

 are carried out, then the relative hydration of the uncommon ions may 

 be determined. The absolute hydration of the ions is of course not 

 determinable. In Table LXXX are given values of the true transference 

 number, the ordinary transference number, and the water transference 



Washburn, Joe. ait. 



