1913] Silver JSTitrate iConcenteation Cells 49 



was determined by the same formula as for aqueous solutions. 

 As these values vary somewhat (see Table III), it seems prob- 

 able that the migration ratios of Ag* and ISTOg" are not constant 

 even for concentrations below o.lA^. Taking K^O.074, the 

 value of V is 0.62. 



SUMMARY 



The electromotive forces of concentration cells containing 

 solutions of silver nitrate in water at 25° are in accord with the 

 I^ernst formula for dilute solutions. Where higher concentra- 

 tions were employed the calculated value of the electromotive 

 force is greater than the observed because the migration ratio v 

 is smaller at the higher concentrations. This affects two factors 

 in the IsTernst equation, viz., ^v/u-^v and log c^/c^. The latter 

 factor is affected because the ratio of the ion concentrations 

 c-i^/co is determined from conductivity measurements and this 

 method of determination is valid only when the migration ve- 

 locity remains constant. The value of migration ratio for 

 dilute solutions calculated from the above results agrees closely 

 with the values found by direct experiment. 



For ethyl alcohol solutions the migration ratio apparently 

 varies even at concentrations below o.l N. The value of v cal- 

 culated from the most dilute solution was 0.62. 



Chapel Hill, N. C. 



