Potential of Electrodes in Stationary Liquids. 33 



the concentration of the solution in ~- , " , i the 



•i cm ° 



, . milamps. ., . , n 



current strength m f— -, t the time m seconds, and n a 



cm.- 



the transport value of the anion. Details of the experiments 

 and results are arranged in the following table. 



Table I. 



A. Copper sulphate solution, concentration 0*204 ^* — '. 



c.c 



Electrode: Platinum-iridinm of available surface 0*7589 cm. 2 

 1^=0-63. 



Current-densitv in . P . 



•i " lime in 



milamps. seconds tUre 

 cm." 1 in u 



Tempera- Diffusion Coefficient 

 cm. 2 



,tT : 



sec. 



2109 



1757 

 1-506 



1042 



790 

 1,053 

 1,566 

 3,297 



16 

 16 

 16$ 



4-58xl0~ b 

 4-24 X10-' 3 

 463 xlO" 13 

 466 xlO - * 3 



Diffusion Coefficient at 

 18° by Formula 



k ™ = l+0-026(T-18)' 



4-86 Xl0 -6 

 4-45 xlO -6 

 4-86 xlO -6 

 4 81X10" 6 



B. Silver nitrate solution, concentration 01 — — — '- 



c.c. 



Electrode as above, n a = Q'52$. 



1-757 



580 



18* 



6-82x10" 



6-73x10" 



According to Wiedeburg* the diffusion coefficient of 

 CnS0 4 at 18° is 4*479 x 1Q- 6 for the concentration 0, and 

 4*226 X 10~ 6 for the original concentration of the preceding- 

 table. The values in the table thus appear somewhat high. 

 The value found for the diffusion coefficient of silver nitrate 

 is very much too low if we take as correct the number 



cm 

 fc 18 =12 , 5xl0- 6 ~ ' .which has been calculated by Nernst 



sec. J 



from the migration velocities of the Ag ' and the NO/ ion f, 

 and which agrees with values extrapolated from Scheffer's 

 determinations of diffusion coefficients J. This fact seems to 



* Wied. Ann. xli. p. G75 (1890). 



t ZUchft. Phys. Chora, ii. p. 400 (1888), 



X Ibid. ii. }>. 628 ( I 3 



Phil. Mag. 8. 6. Vol. 9. No. 49. Jan. 1905. D 



