produced by Electricity. 411 
proached very near each other. When the batteries were highly 
charged, so that the intensity of the electricity was higher, the 
differences were less between the best and worst conductors, and 
they were greater when the charge was extremely feeble. Thus, 
with a fresh charge of a one part of nitric acid, and nine 
parts of water, wires of =4, of silver and platinum five inches 
long, discharged respectively the electricity of 30, and seven 
double plates. 
Finding that when different portions of the same wire plunged 
in a non-conducting fluid were connected with different parts 
of the same battery equally charged, their conducting powers 
appeared in the inverse ratio of their lengths ; so, when six inches 
of wire of platinum of 54, discharged the electricity of ten 
double plates, three inches discharged that of 20, 14 inck that 
of 40, and one inch that of 60; it occurred to me that the con- 
ducting powers of the different metals might be more easily com- 
pared in this way, as it would he possible to make the contacts 
in less time than when the batteries were changed, and conse- 
quently with less variation in the charge. 
Operating in this way, I ascertained that in discharging the 
electricity of 60 pairs of plates, one inch of platinum was equal 
to about six inches of silver, to Pa inches of copper, to four of 
gold, to 3:8 of lead, to about -%, of palladium, and ;* of iron, 
all the metals being in a cooling fluid medium. 
I found, as might have been expected, that the conducting 
power of a wire for electricity, in batteries of the size and num- 
ber of plates just described, was nearly directly as the mass ; 
thus, when a certain length of wire of platinum discharged one 
battery*, the same length of wire of six times the weight dis- 
charged six batteries; and the effect was exactly the same, pro- 
vided the wires were kept cool, whether the mass was a single 
wire, or composed of six of the smaller wires in contact with 
each other. ‘I'his result alone showed, that surface had no re- 
lation to conducting power, at least for electricity of this kind, 
and it was more distinctly proved by a direct experiment: equal 
lengths and equal weights of wire of platinum, one round, and 
one flattened by being passed transversely through rollers so as 
to have six or seven times the surface, were compared as to 
conducting powers: the flattened wire was the best conductor | 
in air from its greater cooling powers, but in water no difference 
could be perceived between them. 
VI. I tried to make a comparison between the conducting 
powers of fluid menstrua and charcoal and those of metals. Six 
inches of platinum foil, an inch and 1-5th broad, were placed in 
© A foot of this wire weighed 1°J3 grain, a foot of the other 6:7 grains. 
3 F 2 a vessel 
