in Cells for Direct and Alternate Currents. 



33 L 



either the carbon or aluminium plate could be observed. The cell 

 was placed in series circuit with another, similar in all respects, 

 except that the distance between the plates was inch instead of 

 i inch, an adjustable resistance, and an ammeter. By means of a 

 reversing switch this circuit could be reversed across the poles of 

 twenty-two storage cells having a potential difference of 44 volts. 

 The temperature of the cell was about 12 C. The negative pole of 

 the storage cells was connected to the aluminium plate and the 

 current adjusted to 3*6 amperes, the potential difference between the 

 aluminium and carbon plates being 4'4 volts, and gas evolved freely. 

 On reversing the connections, that is, placing the positive pole of the 

 charging battery to the aluminium plate, the current, so far as this 

 ammeter could show, was zero, the potential between carbon and 

 aluminium being about 22 volts. The surface of the fluid was 

 maintained in a state of agitation, but no gas was evolved, except 

 in very small quantity, if any. 



The figures in Table I show how the potentials between the 



Table I. 



exploring electrode and the carbon and aluminium plates respec- 

 tively, as also the current, varied in terms of time after reversal 

 took place. The time between the two reversals in Table I was 

 27 minutes. There is no doubt but that the current, when reversal 

 took place from 3*6 amperes, first crossed the zero and acquired an 

 opposite sign, finally coming to zero of the instrument. 



This is an important point, and was fully established during 



