868 Dr. C. R. A. Wright on the Determination of 



suppression by chemical action. When the amount of sup- 

 pression due to this cause is determined and added to the 

 observed amount of decomposition, the total corresponds 

 exactly with the quantity of electricity that has passed. 



(3) In the electrolysis of acidulated water, until the sources 

 of loss of hydrogen other than " diffusion discharge " are 

 eliminated (viz. solution in the fluid, condensation and absorp- 

 tion by the electrode, and action of dissolved oxygen originally 

 present in the fluid), the counter E.M.F. set up when a given 

 steady current traverses a given voltameter is short of its 

 maximum value for that current ; simultaneously a deficiency 

 in the amount of hydrogen collected as compared with that 

 due to the quantity of electricity passing is noticed (even 

 after correction for diffusion discharge) ; whilst on breaking 

 circuit, the rate of fall of the " polarization " of the electrodes 

 is more rapid than its minimum value for that current. On 

 the other hand, as soon as ihe counter E.M.F. reaches its 

 maximum, the deficiency in hydrogen disappears (after cor- 

 rection for diffusion discharge), and the rate of fall of the 

 polarization after breaking circuit reaches its minimum. 

 The more nearly completely the sources of loss are eliminated, 

 the more nearly does the counter E.M.F. set up approach its 

 maximum, the less is the deficiency in the hydrogen collected, 

 and the more nearly does the rate in fall of polarization 

 apjoroach its minimum. 



(4) A theory has been enunciated, and more or less com- 

 pletely demonstrated, which reconciles the hitherto apparently 

 contradictory numerical values obtained by previous obser- 

 vers for the counter E.M.F. set up during electrolysis, the 

 " subsequent polarization " existing after rupture of the cur- 

 rent, and the E.M.F. of gas batteries. In accordance with this 

 theory, the relationships between the current flowing and the 

 counter E.M.F. set up in an electrolytic cell are expressed by 

 the following formula : — 



e=E+[2{(l-n)H}-2(w/0-S(H)] x J. 



(5) In the case of all the electrolytes examined, the value 

 of e is found to increase as the current increases, but at a 

 less rapid rate, so that the curves traced out by plotting 

 currents as abscissas and counter E.M.F. values as ordinates 

 are concave downwards. 



So long as the rate of flow per unit area of electrode sur- 

 face remains the same, the value of e is constant ; i, e. if the 

 electrode surface and the current vary in the same way, then 

 e remains the same. With a given current increasing the 

 electrode surface diminishes the value of e. 



