1883.] the Electromotive Force and Resistance of Batteries. 251 



DIAGRAM IV. 10 f SULPHURIC ACID. 





mfxrature 110" 



210° 



310° 410° 



510° 



610° 



7io a sitr ■ 

























05 



■ -x ' 







110° 



2p° 



3!0° 4,0' 



510" 



610° 



710° 810° 



9!0° 





DIAGRAM V. 20°|° SULPHURIC ACID 





mvc/aiuixXO" 



20" 



310° 



4)0° 



5I0 6 





710" 













"""V"* _ 





































t~"T—\—> 







110° 



20 s 



310* 



4o° 



510° 



6|9" 



7\0° 



W>° 



90° 





DIAGRAM VI.30o|° SULPHURIC ACID 



HrriprrutuJ-eW 210° 310° 



4^0" 5i0° 



6i0° 



710° 8l( 



)° S\0°CentumaJi 





~~~** 











v 

















l|0° 2|0° 310° 



40° 5i0° 



6K>" 



710° 



310" 





Tables VII, VIII, and IX, and plotted out in the curves IV, V, and 

 VI. The different results are for different degrees of saturation. It 

 is evident from an inspection of those tables and diagrams, that the 

 influence of heat on secondary cells is the same in kind as in the 

 Daniell cell, but that it differs very much in degree. Tbe electromo- 

 tive force practically remains constant for all degrees of temperature, 

 but the internal resistance diminishes as the temperature increases at 

 a very steady rate, increasing again as the temperature is lowered. 

 The effect of varying the percentage of acid in solution is not very 

 marked, though as might have been [anticipated from Kohlrausch's 

 ■observations, the 30 per cent, proportion gives the lowest resistance. 

 The mean average reduction in resistance between 0° and 100° 0., is 

 -59'6 per cent. This is shown by the following table : — 





Resistance in ohms. 





Percentage 







Percentage 



of acid. 







of faU. 





0°. 



100°. 





10 



■0752 



•0460 



61 



20 



•0800 



•0457 



57 



30 



•0620 



•0358 



58 



Mean 



•0724 



•0425 



59-6 



