610 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



The Temperature Effect on Cell Voltage. 



17. It must also be true that the isochronal lines of temperature 

 and cell voltage will show a somewhat similar course. For while the 

 resistance is a more complicated function of cell condition than the 

 6. m. f. both factors must be largely determined by diffusion if final 

 analysis were possible. Sections have been made of the isothermal 

 voltage curves of Figure 6 at various times during discharge, and these 



s° 



20° ao 



TeMPERATUBB. 



10° 



^Cf 



Figure 13. Temperature effect on capacity. Plante plates. One hour rate 



of discharge. 



are plotted in the curves of Figure 12. No attempt has been made to 

 determine the e.m.f of the fully charged cell at various temperatures. 



At 35° C. the coefficient of a cell which has been under discharge for 

 30 minutes is about 0.006 volts per degree, w^ile that of a cell which 

 has been running at the same rate for two hours is 0.62 volts per de- 

 gree. [The open circuit temperature coefficient for this acid concen- 

 tration is about .0003 volts per degree (Dolazalek).] 



It should be kept in mind in considering this and the results indi- 

 cated by the curves of Figure 11, that the cell contains throughout 

 the course of each of the curves, exactly the same amount of each 

 of its constituents. The same quantity of electricity has passed 

 through it, and equal amounts of lead, lead peroxide and lead sul- 

 phate are present. The total amount of acid in the whole bulk of the 



