produced by electricity. 437 
larger quantity passing through them, when the cells were 
filled with fluid. 
And a similar circumstance occurred with respect to a wire 
of platinum, of such a length as to leave a considerable resi- 
duum in a battery when only half its surface was used ; yet 
when the whole surface was employed, it became much 
hotter, and nevertheless left a still more considerable resi- 
duum. 
VIII. I found long ago, that in increasing the number of 
alternations of similar plates, the quantity of electricity seemed 
to increase as the number, at least as far as it could be judged 
of by the effects of heat upon wires ; but only within certain 
limits, beyond which the number appeared to diminish, rather 
than increase the quantity. Thus the two thousand double 
plates of the London Institution, when arranged as one bat- 
tery, would not ignite so much wire as a single battery of 
ten plates with double copper. 
It is not easy to explain this result. Does the intensity 
mark the rapidity of the motion of the electricity ? or, merely 
its diminished attraction for the matter on which it acts ? 
and does this attraction become less in proportion as the cir- 
cuit, through which it passes, or in which it is generated, con- 
tains a greater number of alternations of bad conductors ? 
Mr. Children, in his account of the experiments made 
with his battery of large plates, has ingeniously referred the 
heat produced by the passage of electricity through conduc- 
tors, to the resistance it meets with, and has supposed, what 
proves to be the fact, that the heat is in some inverse ratio 
to the conducting power. The greatest heat however is pro- 
