98 Mr. H. Wilde's Experimental Researches 



envelope was formed, which enabled the comparatively feeble 

 current from a single Grove's cell to exhibit, by its prolonged 

 action, electrodynamic ^effects at CD which the powerful, but 

 momentary, alternating currents from the 10-inch intensity- 

 armature were unable to produce. 



165. Proceeding from the liquids in the tub which offered 

 the least to those which presented the greatest amount of resist- 

 ance to the passage of an electric current, a small double coil 

 of twin conductors was immersed in a large glass jar of Gallipoli 

 oil with the ends C, D disconnected. This coil was formed of 

 two separate lengths of cotton-covered copper wire, each ] 50 feet 

 long and "050 of an inch in diameter. 



166. On making and breaking contact between the ends A, B 

 of the double coil and the polar terminals of the 10-inch inten- 

 sity-armature while the coil was immersed in the jar, not the 

 slightest spark, nor any other indication of the passage of a cur- 

 rent through the oil, was obtained — the result being, in this 

 respect, the same as if the ring of twin conductors had been 

 suspended in the air. 



167. That the peculiar arrangement of the double coil was 

 eminently favourable for exhibiting the transmission of a current 

 through a conducting liquid was evident from the fact that 

 when the same coil was immersed in the jar filled with dilute 

 sulphuric acid instead of oil, so powerful was the current trans- 

 mitted through the liquid, that a lsngth of 2 feet of each of the 

 ends A, B, extending from the surface of the liquid to the termi- 

 nals of the electromotor, was made red-hot. This experiment, 

 besides exhibiting the greatest possible difference between the 

 conducting-power of liquids under conditions eminently favour- 

 able for obtaining an electrolytic discharge, also shows with what 

 enormous rapidity the liberation and recombination of the elec- 

 trolytic products takes place; for during the whole time that 

 the ends A, B of the copper wires were maintained at a red heat, 

 not a single bubble of gas made its appearance in the dilute acid 

 in which the double coil was immersed. 



168. I have said that when an electromotor consisting of a 

 single pair of zinc and platinum plates, excited by dilute sulphuric 

 acid, was placed in connexion with a double coil of twin conduc- 

 tors immersed in a vessel of distilled water, the transmission of 

 the current through the water was attended by the liberation of 

 hydrogen from the platinum in a visible manner (149). 



169. As this result has never, to my knowledge, been obtained 

 before by a current of so low an intensity as that from a single 

 pair of zinc and platinum plates, it seemed to me that the anoma- 

 lous exception which Faraday thought he had discovered to his 



