J. H. Reedy — Anodic Potentials of Silver. 



409 



on other influences, such as the concentration of the halogen 

 anion, the resistance of the cell and external circuit, and the 

 cathode potential. From this it is evident that any analytical 

 method, in which it is sought to control the course of the elec- 

 trolysis by regulation of the current strength without regard to 

 the anodic potential, — as has been attempted by various inves- 

 tigators, — is, to say the least, inaccurate and uncertain. 



Estimation of the Halogens.— -Table II contains a summary 

 of the results obtained in the estimation of the halogens. It 

 should be stated that this table contains the results of all the 

 determinations made in which the theoretical conditions were 

 maintained. In a number of experiments the anodic potential, 



Table II. Estimation of the Halogens. 

 (Volume of Solution = 205". ) 







Halogen 



Halogen 





Maximum 



Number 



taken 



found 



Error 



anode poten'l 



of 



Exp. 



grams 



grams 



grams 



volts 



Iodine 



1 



•0620 



•0618 



— •0002 



•205 



Estimations 



2 



•0620 



•0623 



4- -0003 



•190 





3 



•0620 



•0617 



— •0003 



•190 





4 



•0620 



•0620 



•0000 



•190 





5 



•0620 



•0617 



— •0003 



•190 



Bromine 



6 



•0396 



•0386 



— •0010 



•440 



Estimations 



7 



•0396 



•0393 



— •0003 



•400 





8 



•0396 



•0396 



•oooo 



•400 





9 



•0396 



•0393 



— •0003 



•400 





10 



•0396 



•0395 



— •0001 



•400 



Chlorine 



11 



•0177 



•0078 



— •0099 



•520 



Estimations 



12 



•0177 



•0166 



— •0011 



•520 





13 



•0177 



•0168 



— •0009 



•520 





14 



•0177 



•0164 



— •0013 



•520 





15 



•0177 



■0125 



— •0052 



•520 





16 



•0177 



•0162 



— •0015 



•520 



through lack of attention, rose too high, with the result that sil- 

 ver went into solution. Such experiments have been excluded 

 from the table. 



The tendency towards low results in the iodine and bromine 

 determinations is probably only accidental, and the results con- 

 firm the conclusions developed in the study of the conditions 

 involved in the general process. 



But in the case of the chlorine estimations, the deficiencies 

 are not to be attributed to experimental error. In every case 

 except one it was found that silver had gone into solution, and 

 amounts varying from '0003 to '0010 grams in weight had been 

 transported to the cathode. The exception was Exp. No. 15, 

 in which the process was interrupted early, while the galva- 



