CONTRIBUTIONS FROM THE JEFFERSON PHYSICAL 

 LABORATORY, HARVARD UNIVERSITY. 



SOME MINUTE PHENOMENA OF ELECTROLYSIS. 

 By Harry W. Morse. 



Presented by John Trowbridge, December 8, 1909. Received January 6, 1910. 



As the process of electrolysis is usually carried out there is very 

 little opportunity to get any insight into its more minute mechanism. 

 We are accustomed to think of each metal by having its own solution 

 pressure, and by this we mean that it tends to go into solution under 

 an impetus which varies with its position in the electro-motive force 

 series. It is possible to calculate an osmotic pressure which would be 

 just sufficient to balance this solution pressure and which would, if 

 applied, cause equilibrium at the electrode. Under ordinary condi- 

 tions electrochemical reactions are quite perfectly coupled. Equiva- 

 lent amounts are dissolved at the anode and precipitated at the 

 kathode, and it is not infrequent to state Faraday's Law in terms of 

 the amounts thus dissolved and precipitated. But cases are well 

 known where much more care must be taken in the statement of this 

 law, as for example, where the air enters into reaction with one or both 

 of the electrodes, or where the electrolyte itself attacks them. Very 

 frequently a reaction of the form 



M ++ + M met ai^2M + 



causes a loss or gain not proportional to the amount of current which 

 has passed through the electrolytic cell. 



In the case of silver electrodes in a solution of silver nitrate it is 

 usual to sum up the process as follows: — 



During any unit of time after the circuit is closed 



(1) An equivalent amount of silver dissolves at the anode. 



(2) Silver migrates (as silver ion) toward the kathode and nitrate 

 ion migrates toward the anode, each carrying its share of the current 

 in proportion to its migration velocity. 



(3) An equivalent amount of silver separates as metal at the 

 kathode. 



