on the Construction of a Voltaic Apparatus. 35 
which, from the immense quantities given out from so large 
a surface, evolve, on their mutual annihilation, heat sufficient 
to raise the temperature of the platina to the point of fusion. 
With the iron wire, of ^th of an inch diameter, the effect 
is very different, which is explained by the low state of the 
intensity of the electricity ( sufficiently proved by its not caus- 
ing any divergence of the gold leaves of the electrometer ) , 
which being opposed in its passage by the thin coat of oxide, 
formed on the iron wire, at the moment the circuit is com- 
pleted, a very small portion only of it is transmitted through 
the wire. To the same want of intensity is to be attributed the 
total inability of the large battery to decompose the barytes, 
and its general weak action on bodies which are not perfect 
conductors. The small battery, on the contrary, exerts great 
power on imperfect conductors, decomposing them readily, 
although its whole surface is more than thirty times less than 
that of the great battery ; but in point of number of plates, it 
consists of nearly ten times as many as the large one. The 
long continued action of the small battery, proves the utility 
of having the cells of sufficient capacity to hold a large quan- 
tity of liquor, by which much trouble of emptying and filling 
the troughs is-avoided, and the action kept up, without inter- 
mission, for a long space of time, a circumstance, in many 
experiments, of material consequence. Besides this advantage, 
with very large combinations, a certain distance between each 
pair of plates is absolutely necessary , to prevent spontaneous 
discharges, which will otherwise ensue, accompanied with 
vivid flashes of electric light, as I have experienced, with a 
battery of 1 250 four-inch plates, on the new construction. And 
here I beg leave to mention an experiment, which, though not 
E 2 
