494 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



.")() microfarad condenser should not have much internal leakage, as 

 this would run down the voltage of the storage battery too fast. The 

 test-tube cells of the battery naturally have not a large current capac- 

 ity, but they are excellent for giving a steady difference of potential 

 and small charges such as are required for these experiments. In the 

 case of each condenser the first residual throw is assumed to be zero. 



The mean results reduced for the experiments up to March 10 are 

 shown in the preceding nine tables. 



0.0005 



0.0010 

 TIME OF CHARGING. 



0.0015 



Figure 6. (Tables XXVIII, XXX, XXXI, XXXIII.) 



By comparing these summarized results of Tables XI-XIX with 

 those which are to follow, we see that they do not all agree very well. 

 But there is a substantial similarity in the behavior of the various 

 condensers, and some condensers, as " Par. A," "Par. B," "Par. AA," 

 and "Par. BB," show very close agreement with results as determined 

 more accurately later. The results from the mica condensers are not 

 so good. 



It will be seen that the condensers of plain mica sheets show a very 

 much greater residual capacity for long charges than the condenser 

 mule of shellacked mica sheets. This is hardly what we should have 

 expected, according to Maxwell's heterogeneity theory. 



