276 Dr. Fai'aday's Experimental Researches in Electricity, 



yet no trace of acid or alkali from the sulphate of soda ap- 

 peared. 



977. From these experiments it may, I think, be concluded, 

 that a solution of sulphate of soda can conduct a current of 

 electricity, which is unable to decompose the neutral salt 

 present; that this salt in the state of solution, like water, re- 

 quires a certain electrolytic intensity for its decomposition ; 

 and that the necessary intensity is much higher for this sub- 

 stance than for the iodide of potassium in a similar state of 

 solution. 



978. I then experimented on bodies rendered decomposa- 

 ble by fusion, and first on chloride of lead. The current was 

 excited by dilute sulphuric acid without any nitric acid be- 

 tween zinc and platina plates, fig. 1 5., and was then made to 

 traverse a little chloride of lead fused upon glass at a, a paper 

 moistened in solution of iodide of potassium at h, and a gal- 

 vanometer at g. The metallic terminations at a and b were 

 of platina. Being thus arranged, the decomposition at b and 

 the deflection at g showed that an electric current was passing, 

 but there was no appearance of decomposition at a, not even 

 after a metallic communication at b was established. The 

 experiment was repeated several times, and I am led to con- 

 clude that in this case the current has not intensity sufficient 

 to cause the decomposition of the chloride of lead ; and 

 further, that, like water (974.), fused chloride of lead can 

 conduct an electric current having an intensity below that re- 

 quired to effi^ct decomposition. 



979. Chloride of silver was then placed at fl, fig. 15., instead 

 of chloride of lead. There was a very ready decomposition 

 of the solution of iodide of potassium at Z>, and when metallic 

 contact was made there, very considerable deflection of the 

 galvanometer needle at g. Platina also appeared to be dis- 

 solved at the anode of the fused chloride at a, and there was 

 every appearance of a decomposition having been effected 

 there. 



980. A further proof of decomposition was obtained in the 

 following manner. The platina wires in the fused chloride at 

 a were brought very near together (metallic contact having 

 been established at /;), and left so; the deflection at the gal- 

 vanometer indicated the passage of a current, feeble in its 

 force, but constant. After a minute or two, however, the 

 needle would suddenly be violently affected, and indicate a 

 current as strong as if metallic contact had taken place at a. 

 This I actually found to be the case, for the silver reduced by 

 the action of the current crystallized in long delicate spiculae, 



