JOURNAL 



OF THE 



WASHINGTON ACADEMY OF SCIENCES 



Vol. IV FEBRUARY 19, 1914 No. 4 



ELECTROCHEMISTRY. ~Compariso7i of the silver and iodine 

 voltameters and the determination of the value of the faraday. 

 G. W. ViNAL and S. J. Bates. To appear in full in the Bul- 

 letin of the Bureau of Standards and Journal of American 

 Chemical Society. Communicated by E. B. Rosa. 



A form of iodine voltameter was devised by Washburn and Bates 

 and described by them in the J. Am. Chem. Soc. 34, 1341. This 

 instrument was found to be of about the same order of reproduci- 

 bility as the silver voltameter. Because of the reversibility of 

 the reactions taking place at the anode and the cathode and the 

 character of the deposit which precluded the possibihty of inclu- 

 sions of foreign material it seemed a desirable instrument to 

 use in the determination of the faraday, especially since the values 

 for this constant had heretofore been based on the silver measure- 

 ments alone. 



Accordingly arrangements were made for a comparison of the 

 silver and iodine voltameters at the Bureau of Standards during 

 the summer of 1913. The operation of the iodine voltameters 

 was in general the same as previously described by Washburn and 

 Bates. The silver voltameters were of the porous cup and Smith 

 form following the usual procedure of the Bureau of Standards. 

 Since the same current passed through the silver and iodine 

 voltameters, the ratio of silver to iodine may be immediately 

 calculated. As a result of ten experiments in each of which 

 several voltameters of both types were employed we find the ratio 



^^ = 0.85017 

 Iodine 



69 



