THE ALUMINUM ELECTROLYTIC CONDENSER 



47 



be made by having two electrodes of film-forming metal in the same 

 solution, the electrical relations between the "filmed" electrodes 

 being the same in this case as in the series-opposed arrangement of 

 two asymmetrical cells. In either case one or the other of the film- 

 forming electrodes opposes the flow of current during each half cycle. 



If we consider the conditions that exist at the instant of maximum 

 potential in one direction, the electrode that is then andde acting as a 

 condenser, receives its maximum charge. As soon as the potential 

 begins to decrease from this maximum the accumulated electricity 

 begins to flow from the charged plate through the circuit, but in so 

 doing the opposing film-forming electrode becomes an anode, enabling 

 it to hold the charge given up by the discharging electrode. 



In this way, as the alternating potential varies between maximum 

 values in each direction, the charge is transferred from the capacity 

 provided by one film-forming electrode to the other, the sum of the 

 charges on these two electrodes at every instant remaining constant. 

 It can be shown that two series-opposed asymmetrical cells of capacities 

 Ci and C2, or two "formed" electrodes of these capacities in the same 

 electrolyte, have a resulting capacity equal to 



Ci + Q 



As illustrated in Table II, which gives the results of measurements 

 on two asymmetrical cells formed to different voltages and connected 

 in various series combinations, it will be noted that this relationship 



TABLE II 

 Measurements at 60 Cycles 



Biasing 



Potential 



Volts D.C. 



Capacity 



Microfarads 



Equivalent 



Series Res. 



Ohms 



Condenser "A" . 

 Condenser "B " , 



"A" and "B" series — aiding... 



"A" and "B" series — opposing 



"B" positive 



No bias 



"A" positive 



Calculated from measurements of "A" and 

 "B" 



24.6 



44 



•50 

 43.8 



.25 



[37.3 



[18.3 







12 



24 



1529 



962 



587 

 582 

 588 



588 

 588 

 594 

 588 

 588 



589 



0.165 



0.23 



0.385 



0.38 



0.38 



0.395 



0.38 



0.385 



0.39 



0.39 



0.395 



^ Zimmerman, Trans. Am. Elecirochem. Soc, 7, 323 (1905). 



