On the Conducting Power of Iodine, &¢. for Electricity. 131 
¥, any current that passed would be rendered evident by the 
decomposition of the iodide of potassium. 
» $. Iodine was fused in the tube G, and the end of its two 
wires, I and H, were placed on the papers E and_F, as soon 
as the iodine was solid; not the least spot of iodine was per- 
ceived at E or H, though the battery employed consisted of 
sixty pairs of plates, four inches square, in very strong action: 
a small piece of wire was then made to connect I and H, just 
where they are fused into the glass tube; and though they were 
but momentarily connected, yet a dark spot of iodine was pro- 
duced ; thus proving that the only interruption to the current 
was that in the tube G, between the wires H and I. 
Fig. 1. 
D . EK 
4. ‘The iodine was then replaced by a solution of iodine in 
water; the current passed immediately, and produced its full 
effect at A and H: the water only, however, was decomposed, 
and no peculiar action was occasioned. But this is certainly no 
proof that iodine is at all a conductor ; we very well know that 
sulphuric acid added to water improves its conducting power, 
and so do phosphoric and sulphurous* acids, and man 
other acknowledged nonconductors; indeed, were it not for the 
addition of certain nonconducting substances, such as sul- 
phuric acid, the decomposition of water would hardly be ef- 
fected by the voltaic battery. Again, M. De la Rivet has 
remarked that bromine and chlorine are nonconductors, and 
' * See Phil. Trans. 1834; Faraday’s Seventh Series, No. 755. for Lond. 
and Edinb. Phil. Mag., vol. v. p. 257.—Enrr.) 
« t Annales de Chimie et de Physique, 1827, vol. xxxv. 
