WORK AB80i:i!i:i> IN I I.KOTIIOLYSIS. 41 



economical efficiency, it is useful to know the proportion exist- 

 ing between these two electromotive forces, or, what amounts 

 to the same, between their two corresponding resistances. The 

 determination, by means of calculation, of these two quantities, 

 is not an easy matter, as the chemical actions are often of a very 

 complex nature, and the elements of the metallic resistance are 

 extremely varied and subject to great alterations even during 

 the course of a single operation. 



If the intensity C is measured in amperes, the fall of poten- 

 tial E between the electrodes, in volts, the resistance evidently 



E 

 isR = E. 



Calling E' the counter electromotive force, and E' the 



"P _ TT' 



metallic resistance of the bath, we shall have R' = ~ . 



C 



In the industrial practice and for every electrolyte, E' can be 

 considered as being constant, and E' as variable, owing to the 

 differences of heat, saturation, acidity, &c., which, although they 

 may be slow in manifesting themselves, nevertheless occur 

 with certainty for the whole duration of the operation. It can, 

 however, be assumed that K' is constant during a short interval 

 of time. 



M. Marchese advises estimating E and C on the electrolyte 

 which is under observation, then to alter the regimen by 

 increasing or reducing the speed of the dynamo machine and 

 make some new observations. 



Thus at a normal speed, we have, for example : 



For a greater speed we obtain 



E + e - E' 





+ c 

 We deduce from these two equations : 



E' = E - '-? 







