52 IOWA ACADEMY OF SCIENCE 



Neustadt and Abegg 5 investigated the electrode potentials and 

 electromotive forces of a number of cells containing solutions of 

 the salts of silver, lead, copper, mercury, cadmium, and zinc. 

 The solvents used were water, methyl alcohol, ethyl alcohol, ace- 

 tone, and pyridine. In all cases the half cell, Ag-AgN0 3 — , con- 

 stituted one-half of the cell. Since the potential differences in 

 methyl alcohol, ethyl alcohol and acetone are approximately equal 

 to those in water, they concluded that the solution pressures of 

 any one of the metals in these four solvents are approximately 

 equal. The considerably lower values obtained for solutions in 

 pyridine are attributed to extremely low ionic concentration. 

 They also consider that, possibly, silver nitrate is ionized in pyri- 

 dine solution according to the equation: 



Ag 2 (N0 3 ) 2 ±^Ag 2 N0 3 + N0 3 



Experiments were made using a number of solution chains as 

 liquid junctions in an attempt to eliminate the diffusion potential. 



Getman 6 and Getman and Gibbons 7 measured the potentials of 

 cadmium and zinc in alcoholic solutions of their salts. In each 

 case the normal calomel electrode constituted the other half of 

 the cell. For both metals it was found that the electrode 

 potentials become more negative as the concentration of the salt 

 increases. Since the effect of concentration is just the reverse 

 of what is found for aqueous solutions, they concluded that the 

 applicability of the Nernst equation is very improbable. 



Bell and Field 8 measured the electromotive forces of concen- 

 tration cells in water and in ethyl alcoholic solutions of silver 

 nitrate. Rearranging the Nernst equation to the form: 



IT = 2v . RT. log 10=K 



log 10 j^ u+v nf 

 c 2 

 they calculated the values of K. The values thus obtained varied 

 between 0.0560 and 0.0623. Assuming the value 0.0623, they 

 calculated the transport number of the anion of silver nitrate in 

 water to be 0.523. Since, however, the value of K varies so 

 widely, they concluded that the transport number must change 

 with the concentration of the salt. 



6 Zeit. physik. Chem., 69, 486, 1909. 

 •Am. Chem. Jour., 46, 117, 1911. 

 'Ibid., 36, 1630, 1914. 

 "Jour. Am. Chem. Soc, 35, 715, 1913. 



