266 Mr Skinner, On the Electro-chemical equivalent of Carbon, 



In farther support of this view of the persistence of the 

 permanganate ion during electrolysis some experiments were made 

 in which a current was passed through potassium permanganate 

 and the escaping gases were collected. 



When a current is sent through potassium permanganate using 

 platinum electrodes, oxygen is set free at the anode and hydrogen 

 at the cathode. The volume of oxygen is very nearly equal to 

 that set free in an acidulated water voltameter through which the 

 same current passes, whereas the volume of hydrogen is very 

 variable. When the cathode is clean little hydrogen is set free, 

 but after a time the cathode becoming coated with black man- 

 ganese dioxide, the hydrogen escapes more rapidly and begins to 

 approximate in volume to double that of the oxygen. The follow- 

 ing measurements illustrate this, and as the current was also 

 measured the influence of current-density at the electrode can be 

 traced : 



Table III. 



