3S4 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



tically constant capacity at all voltages below the forming voltage. 

 The curves of Figures 11 and 12 may be regarded as'tests showing the 

 approximation to true condenser action which is attained with alumin- 

 ium electrodes. For an ordinary mica or paper condenser the rate of 

 leak during insulation is of such a form that the charge remaining in 

 the condenser is 



5 

 o 



o 



< 

 a. 



o 



OI>° 



time • seconds 

 Figure 13. 



Capacity vs. insulation time at various forming voltages. Long charge. 

 Long discharge. 



If the logarithm of the remaining charge is plotted against insula- 

 tion time, the resulting curve is a straight line. Figure 16 shows the 

 curves obtained by plotting the data of Figure 12 in this way. It is 

 quite evident from these curves and from the results of time measure- 

 ment on charge and discharge that we are not dealing with a true con- 

 denser. It will be noticed that at voltages far below that of formation 

 the curve of leak follows the logarithmic formula quite closely. In all 





