608 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



Overcharge. 



14. The resistance during overcharge seems to be a most variable 

 factor. It risps and falls a thousandth of an ohm or so in one cell 

 but has no regular course. 



The disturbing factor must be the escaping gases as there is no 

 other action going on in the cell. 



/^ £0° 30° M" SO* 



Figure 1 1 . Temperature effect on resistance after various periods of discharge. 



SuLPHATED Plate. 



15. Measurements were made over a period of a month or more on 

 a nearly discharged plate. It showed no characteristic course whatever 

 but varied from day to day over a range of several thousandths of an 

 ohm, rising slightly during the first three weeks and then falling again. 

 We evidently did not arrive at a sulphated condition in the usual 

 understanding of the word. 



The Temperature-effect on Resistance. 



16. The curves of Figure 5 show the course of change of resistance 

 during discharge at constant rate and constant temperature. They are 

 isothermals. From these it is possible to construct isochronal curves 

 of resistance vs. temperature, the isochronal curve corresponding to the 

 fact that the same total amount of active material has been effected in 

 each case, but at a dijBferent temperature. These curves are of special 



