Edison Effect in Glow Lamps. 



95 



double carbons, further experiments were performed on the 

 discharging power of the hot and cold electrodes for positive 

 and negative electricity. The two carbons could be rendered 

 incandescent either simultaneously or singly by two sets of 

 insulated secondary batteries attached to each respectively. 

 For the sake of distinction we shall speak of the large carbon 

 loop in this bulb as the L loop and the smaller one as the 

 S loop. A condenser of 5 microfarads capacity (see fig. 20) 



Fig. 20. 



CONDENSER 



was employed, which was charged to a potential of about 

 50 volts. When the positive plate of this charged condenser 

 was attached to the carbon L and the negative side to the 

 carbon S, then on making L incandescent by its own 

 insulated battery and keeping S cold, the condenser was 

 found not to be discharged when insulated and tested by a 

 galvanometer. If, however, the same charged condenser was 

 connected in the same way to the two carbons and the 

 carbon S, to which the negative side of the condenser was 

 attached, was made incandescent, the condenser was instantly 

 discharged. If the direction of the charging of the condenser 

 was reversed the same rule was found to hold good. The 

 condenser was discharged if the negatively charged plate of the 

 condenser was connected to the incandescent carbon loop, but not 

 if it was connected to the cold carbon loop. Beginning with 

 the condenser charged and connecting it in between the two 

 carbon loops, neither of them being incandescent, then the 

 condenser was discharged instantly if that loop to which the 

 negatively charged side of the condenser was attached Mas 

 rendered incandescent, but not discharged if the loop to 

 which the positive side of the condenser was connected was 

 rendered incandescent. If both loops were rendered inean- 



