PAPERS OX CHEMISTRY AXD PHYSICS 317 



The charging source was then disconnected, and the 

 cells discharged through a resistance at a rate about 

 equal to that of charging. After they were discharged 

 the cells were allowed to stand for a day and then chai-ged 

 as before, but now in the opposite direction, forming lead 

 peroxide on the plate which had previously been negative. 

 When the cells were again gassing freely the same pro- 

 cedure as before was followed in discharging them. Tlie 

 above cycle was then repeated until they seemed to have 

 reached their maximum capacity. About 15 such cycles 



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Figure 2. 



were required, after which they were charged and dis- 

 charged a few times without reversing the polarity, and 

 after a final charge were put into use. 



In charging the cells the trays containing them were 

 always placed in parallel; thus the charging voltage 

 necessary was but little in excess of that of each tray. 

 Since there are twenty cells in each tray the charging 

 voltage need not exceed 45 volts. However, to obtain a 

 high voltage on discharge when using them the trays must 

 be connected in series. Thus five trays when fully 

 charged give when connected in series 200 volts. 



