110 Dr. J. Hopkinson and Messrs. E. Wilson and F. Lydall. 



FIG. 4. 



In tlie same way the Curve B was plotted for the E.M.F. between 

 D and E, giving the current in terms of time. Hence the area of 

 this Curve B up to any point, plus a constant, is proportional to the 

 quantity of electricity corresponding to that point. This is shown in 

 Curve C, which is the integral of B. The three curves, Nos. 1, 2, 3, 

 in fig. 5, have been plotted from figs. 2, 3, 4 respectively, and show 

 the cyclic variation of the potential across the cells in volts, and the 



Table T. 



1 sq. cm. represents J rolt x 10~ 2 coulombs. 



