350 Mr. W. H. Preece. [May 21, 



every hour, and sometimes every half -hour, (1) of the strength of 

 current flowing through ; (2) of the electromotive force ; and (3) of 

 the density of the liquid of one or more of the cells. The relation 

 of these three quantities tells me the condition of the charge. The 

 accompanying diagrams are typical cases. 



Curre7tt. J 3 Cells. 



Specific Gravity, 



