44 



ELEMENTS OF ELECTRICITY AND MAGNETISM. 



and so on, the electromotive force being measured in each case 

 on open circuit (the cell being disconnected from the circuit to 

 which it delivers current and connected to a voltmeter for a 

 moment when it is desired to read its electromotive force). 



140 



130 



\ 



14 16 

 minutes 



Fig. 19. 



22 24; 



28 3<* 32 



When a voltaic cell has been polarized by delivering current 

 for some time, its electromotive force rises slowly when it is left 

 standing on open circuit. This recovery of a voltaic cell from 

 polarization is due chiefly to the refreshing of the electrolyte in 

 the neighborhood of the electrodes by the slow diffusion of the 

 acid or salt from distant portions of the electrolyte to the surfaces 

 of the electrodes. The ordinates of the curve BB in Fig. 19 

 show the increasing values of the electromotive force of a dry 

 cell standing on open circuit after it has been allowed to deliver 

 current for some time. 



BRANCHED CIRCUITS. 



23. Series and parallel connections. When two portions of an 

 electric circuit are so connected that the entire current in the 

 circuit passes through both portions, the portions are said to be 



