INDUCTANCE AND CAPACITY 377 



The resistances Ri and Rz and their leads must be thoroughly 

 insulated. 



The effect of any considerable leakage in C x during the period 

 of charging, is practically to shunt R i by the leakage resistance, 

 so, to get equal quantities on the condensers, RI as unplugged in 

 the resistance box must be made larger than if the condenser 

 had been of the same capacity and devoid of leakage. Thus the 

 apparent capacity will be too small. 



In this case, the procedure recommended is to use instead of 

 the resistance unplugged in the box, the parallel resistance of RI 

 and the condenser under test. This necessitates a measurement 

 of the insulation resistance of the condenser. The period be- 

 tween charging and mixing must be made as short as possible, 

 since leakage during this time will cause the charge on the un- 

 known to be too small, which will necessitate an increase in RI 

 above the proper value. Leakage during mixing will reduce, by 

 shunting, the quantity to be discharged through the galvanometer 

 and will thus diminish the sensitiveness of the method. 



If absorption be present, it is necessary to adopt some definite 

 cycle of operations in order to obtain comparable results, for the 

 behavior of an imperfect condenser depends to a certain extent 

 on its previous history, that is, on the voltage to which it has been 

 subjected, the time of electrification and the duration of the charg- 

 ing and mixing periods, together with the completeness of the 

 discharge. 



As the absorbed charges reappear gradually and as it is the 

 free charges which are to be neutralized, the key K s must be closed 

 for only an instant, when observing the galvanometer. The 

 condensers should be completely discharged between the 

 observations. 



Gott Method for Comparing Capacities. 12 The connections 

 for Gott's method are shown in Fig. 223. If condensers are being 

 compared, acbd including the galvanometer circuit is a perfectly 

 insulated system. The condensers being discharged, the key KI 

 is depressed, thus sending a current through the circuit cad and 

 charging the condensers C x and C P in series. Then 



7d RN 



