400 Mr. E. Solly’s father Experiments on Electric Conduction. 
mere aspect of certainty, in favour of those conclusions, they 
substitute certainty itself. 
London, April 9, 1836. 
a 
LXXII. Further Experiments on Conducting Power for Elec- 
tricity.* By Evwarp So.ty, Jun., Esq. 
15. [* my former communication I said that I had found 
iodine when solid to be a nonconductor, but I did not 
describe any experiments made with it in the melted state, 
This perhaps may have appeared an omission, the more so after 
Dr. Inglis’s note (the contents of which had not, however, been 
communicated to me,) had been appended to my paper; but I 
had been advised to lose no time in describing such of my ex- 
periments as were in opposition to Dr. Inglis’s statement that 
“jodine is a conductor”.+ What follows now will explain 
that apparent omission. 
16. In all my original experiments I had found iodine to be a 
nonconductor in the fluid as well as the solid state; but on the 
present occasion, when I was led to repeat them by the above- 
mentioned statement, I was not a little surprised to find the 
iodine, when rendered fluid by heat, become a conductor. 
‘That a substance acting as iodine does should not be similar 
as to conducting power when fluid to what it is when solid, 
(as all known substances that have been as yet examined are, 
excepting only such as are electrolytes, and also perhaps the 
periodide of mercury,) but should appear a conductor upon 
assuming the liquid state, was so singular, and so contrary 
to my previous results and preconceived views, that I was in- 
duced to multiply my experiments; they continued unsatis- 
factory, and they were the more so as the iodine did not 
always appear a conductor but sometimes a nonconductor, 
and then, when it did appear a conductor it did ina very feeble 
manner, and with great uncertainty. 
17. Iwas therefore led to doubt the purity of the iodine which 
I was using, and this seemed the more probable as it was 
from a different source from that which I had employed in 
the original experiments; and in the means which I had be- 
fore described for examining conducting power it was impos- 
sible the wires could touch, and therefore the objection which 
the use of loose wires would have introduced was avoided. In 
consequence I procured some perfectly pure iodine sublimed at 
a very low temperature, and ascertained that that which I had 
* Communicated by the Author: see our Number for February, p. 130. 
+ Lond. and Edin. Phil, Mag., No, 43. p. 129. 
