Mr Skinner, On the Electro-chemical equivalent of Carbon. 265 



current the electrolysed permanganate was collected and titrated 

 against the ferrous solution. The change in the number of cubic 

 centimetres of iron solution required measured the loss of per- 

 manganate. 



The following results were obtained. 



Table II. 



Since the current and time are known it is possible to calculate 

 the weight of permanganate which would be decomposed by the 

 corresponding quantity of electricity. The equivalent weight of 

 potassium permanganate is 158, and the electrochemical equivalent 

 of hydrogen is 'OOOOlOoS per ampere-second, and hence the E.C.E. 

 of KMn0 4 is '00164. This represents the amount in grammes 

 decomposed by one ampere per second, and from it we can 

 calculate the weight of permanganate equivalent to the quantity 

 of electricity for each of the above experiments. This gives : — 



Experiment I. 0*69. 

 Experiment II. 0'35. 

 Experiment III. 0'652. 



N 

 Since 100 c.c. of j- KMn0 4 contain -316 gramme it follows that 



sufficient electricity has been conveyed to decompose all the 

 permanganate more than twice in the first experiment. The 

 colour and oxidising power have however remained. To explain 

 this, permanganic acid or potassium permanganate must have 

 been reformed. According to this view the following expresses 

 the action in the divided cell : 



Before 

 O^H^ - 2 Mnol -2K - SQ^K - 20H^~ 2H 



After 



1 The Platinum anode was bright and clean after the experiment. 



