48 
the amount of zinc or other metal electrolytically dissolved, 
and of the quantity of acid or other electrolyte required in 
sustaining such action. 
The theory of Ohm would lead us to calculate the expense 
as in direct relation to the force developed, as well in a com- 
bination of elements as in the case of a single pair. A 
hasty application of the fact that the force of the current is 
in proportion to the electrolytic action might also lead to the 
same conclusion. 
There is, however, a material difference in the consump- 
tion of metal in a pair of elements and in a compound 
battery ; in the first the force is as before shown, F = R ^_ ^ 
and the consumption of metal and acid is in proportion to 
the force ; in the second, F = " E . , and the consumption 
n K -j- r 1 
of metal and acid is n F, that is, the equivalent of the force 
is consumed in each cell of the battery. 
Although the rationale of the last-mentioned fact was, I 
believe, partly suggested by Volta, it is not to be found in 
many of the popular treatises ; and as Volta's explanation is 
applicable to the contact rather than the chemical theory, 
and although it points out why the force is only equivalent to 
one cell, (though such fact was unknown to him,) it does not 
point out distinctly why the electro-motive force or intensity 
is increased in proportion to the number of pairs. Ohm's 
theory, on the contrary, demonstrates the increasing intensity 
as an accumulation of electro-motive force, but does not 
account for the consumption of metal in each cell. 
I fear I may not be able to express my ideas very dis- 
tinctly on this head, without drawing your attention to some 
elementary details. If we take a piece of zinc and a piece 
of platina, and place them in diluted sulphuric acid, con- 
necting them so as to form a closed circuit of a single pair 
of elements ; from whatever part of the circuit we consider 
the action as commencing, we shall have the following 
