Art. LX.—On the Conductivity of certain Substances hitherto supposed to be Non-conducting for Voltaic Electricity.

Transactions and Proceedings of the Royal Society of New Zealand, Volume 29, 1896, Page 581

Art. LX.—On the Conductivity of certain Substances hitherto supposed to be Non-conducting for Voltaic Electricity. By William Skey, Analyst to the Department of Mines. [Read before the Wellington Philosophical Society, 17th February; 1897.] It is generally supposed, and with apparent good reason, that all substances may be polarised, but I do not know that it has yet been proved or asserted that generally all substances are conductors of voltaic electricity, but that such is the case the following results of certain experiments of mine appear to show:— (1.) A piece of copper wire, heated in an oxidizing flame its metallic aspect has quite disappeared over the whole surface, then placed in a voltaic circuit with mercury as the anode and cathode, does not break the current, or even reduce it to any notable extent.

(2.) Gold, also platinum, oxidized or sulphurised until they will not amalgamate in clean mercury, can be substituted for copper in the above experiment with similar results. (3.) Silver, also copper iodized until of a pale-yellow or whitish aspect, can be substituted for copper in experiments, with the same results.(4.) A smooth dry platinum wire plunged in melted beeswax, sealing-wax, or guttapercha, and dipped in again and again until the coating acquired is to be easily seen over its entire surface, can also complete the interpolar connection on dipping its free ends into mercury poles. The conductivity of certain thin films for electricity explains, as I think, the very contradictory statements that have been made respecting the capacity or the incapacity, of argentic sulphide to conduct electricity. Long ago Professor Faraday placed this compound among the electric conductors; but that it really does class as such has been disputed, and still is, I believe, disputed. In 1876* Trans. N.Z. Inst., vol. viii., p. 345. I showed, and, as I think, very clearly, that Faraday's statement is correct. Now, I used very thin films of this sulphide in the experiment I made for settling the point in question, and I suppose that those experimentalists who get different results from those of Faraday used the sulphide in a massive form, and gave contact by only a very small extent of surface. If this surmise of mine is correct the whole matter in dispute is at once explained, and it must be allowed that this compound (argentic sulphide) is an electric conductor, but a feeble one.