![Thumbnail: [Volume 8, 1875 page 345]](/journals/rsnz/images/rsnz_08/thumbnails/rsnz_08_00_0389_0345_ac_02.gif)
Art. XLVIII.—Notes on the Electric and Chemical Deportment of Argentic Sulphide.
In a paper I have given * on the Conducting Power of Sulphides, it is stated that Argentic Sulphide is a good conductor of electricity for a sulphide. I find, however, since this table was compiled that the deportment of this substance into electric currents is a subject which has given rise to some controversy, and that the results as published leave a uniform impression upon chemists that Argentic Sulphide is not an electric conductor in the sense this is usually and properly taken—i.e., not a conductor as a metal is without decomposition.
Thus Professor Faraday supposed it “conducts electricity like a metal, without decomposition; its conducting power, however, increasing with rise of temperature;” while Hittorf is said to show “that, when this compound is free from metallic silver, it conducts only in proportion as it is decomposed.”
A knowledge of these conflicting opinions, and of the fact that their tendency is, as the matter now rests, one of antagonism to that of my own opinion on the subject just quoted, induced me to repeat the experiments
[Footnote] * “Trans. N.Z. Inst.,” Vol. IV., Art. LI.
![Thumbnail: [Volume 8, 1875 page 346]](/journals/rsnz/images/rsnz_08/thumbnails/rsnz_08_00_0390_0346_ac_02.gif)
upon which my opinion was founded, and with, such modification as I thought might best conduce to results informing us correctly on this subject. Taking three plates of pure silver, which had been thickly enfilmed with, this sulphide, by twenty-four hours immersion in a strong solution of sodic sulphide, I well washed and thoroughly dried them, but without disturbing these films; then placed them gently on each other, and connected the outside ones with a feeble battery of one cell, which was attached to a galvanometer, when I found an electric current was still indicated, and which was not notably less in quantity than that which was indicated when these plates were out of the circuit.
The same result followed when the silver plates were heated to 300°F. and even used in this experiment while at a temperature approximating to this.
I, therefore, conclude that Argentic Sulphide can be, as I have maintained, a conductor of electricity, and, for a sulphide, a very good one.
Regarding the chemical deportment of this substance (Argentic Sulphide), I find, contrary to what is alleged respecting it, that it is soluble in cyanide of potassium, and at common temperature, and I may state in this connection that auric sulphide is also soluble in this salt; platinic sulphide appears scarcely so, even in a hot solution of it, though sulphur is detectable in this solution afterwards by the nitro-prussic test.
I further find that Argentic Sulphide is not, as heretofore supposed, un-attacked by mercury, but is decomposed, though very slowly, by it, mercuric sulphide resulting, attended by amalgamation of the silver thus liberated. Auric sulphide is also very slowly decomposed in the same way; plumbic sulphide, however (as galena), is not.
It will be seen, therefore, that these sulphides in their deportment with mercury behave exactly as we should expect from the electrolytic results I have given in respect to them in my paper on the Electro-motive Power of Gold and Platina in Sulphides, * both silver and gold being there stated to be negative to mercury in sulphide of sodium, and lead positive thereto. Indeed I may state that it was the knowledge of the elytrolytic behaviour of the metals above named which induced me to try for the decomposition of argentic and auric sulphide by mercury.
In this connection I would further inform you that this sulphide (argentic) appears decomposed by chloride of copper alone, although it is stated not to be affected by this salt, except in the presence of an alkaline chloride. Theoretically, indeed, it should be decomposed by this auric salt unaided, as sulphur has a greater affinity for copper † than it has for silver, and
[Footnote] * “Trans. N.Z. Inst.,” Vol. IV., Art. LII.
[Footnote] † Ibid.
![Thumbnail: [Volume 8, 1875 page 347]](/journals/rsnz/images/rsnz_08/thumbnails/rsnz_08_00_0391_0347_ac_02.gif)
chlorine has a greater affinity for silver than for copper. There is no doubt, however, that the forming of this chloride of silver stops the action at a point at which we cannot readily distinguish that any action has taken place.