380 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



We have also found occasionally curves similar to that marked 

 AB. This appears to correspond to a condition of formation inter- 

 mediate between the two others. 



There is evidently a close connection between the data of Figure 6 

 and the results to be expected from a study of an aluminium con- 

 denser under the action of an alternating current. As will be seen 

 from succeeding figures, the relation will be a complicated one, because 

 of the influence of insulation time and discharge time. 



.04 .06 



TIME • SECONDS 



Figure 9. 



Discharge curves at higher voltages for fully formed plate, as in Figure 8. 

 Plate formed at 340, charged at 195 volts. 



4. Short Discharge. — Figure 7 shows the arrangement of apparatus 

 for measuring the apparent capacity during a short time of discharge. 

 The insulation time is kept constant at 0.001 second. The charging 

 time, which determines a difference in capacity, as shown by the 

 previous figure, has been given two different values. As shown in 

 the figure, the apparatus is arranged for long charging times, the 

 upper switch being closed and thus connecting the cell with the 

 charging battery. The falling weight opens the charging circuit and 

 closes the discharge circuit after the period of insulation ; the weight 

 falling further opens the galvanometer circuit when it strikes the 

 lower switch. The apparatus for measuring the capacity for short 



