1 86 Mr. G. J. Knox on the Direction and Propagation 



phsenomena of the light and heat developed ; or whether we 

 adopt the gross conception of the passage of a fluid ; still it is 

 important to determine if the electric force passes along the 

 surface of the interposed substance, or through the interior of 

 its mass. 



Dr. Faraday* has shown that water will convey a feeble 

 current of electricity, without undergoing electrolyzation. To 

 determine whether, under such circumstances, it will convey 

 an electrical current along its surface or through its substance, 

 a glass tube, ten feet long, and half an inch internal diameter, 

 bent in the centre twice at right angles, was filled with distilled 

 water. Two copper wires, twenty feet long, having platina 

 wires soldered to their extremities, were inserted in barometer 

 tubes of six feet in length, the platina wires being sealed in 

 the tubes within half an inch of their extremities. The other 

 ends of the copper wires were connected with a delicate gal- 

 vanometer, and a constant battery of successively one, two, 

 four, &c., pair of elements. 



On immersing the platina wires in the liquid, their relative 

 distances from each other should decrease if the current passes 

 through the water, but should increase if it passes along the 

 surface, the deflexion of the galvanometer indicating the path. 

 With one pair of elements there was no deflexion of the gal- 

 vanometer ; with two pair of elements there was a slight de- 

 flexion visible through a lens, which increased slightly on im- 

 mersing the platina wires in the liquid. With four pair of 

 elements, a deflexion of two degrees took place when the pla- 

 tina wires were on the surface of the water ; a deflexion of 

 four degrees when they were immersed to the bottom of the 

 tubes. As the number of alternations in the battery increased, 

 so did proportionably ihe comparative deflexions of the gal- 

 vanometer; the experiments proving that water, whether un- 

 dergoing electrolization or not, conveys an electric current 

 through its substance, and not along its surface, and that the 

 decomposition of the water is an effect produced by the pas- 

 sage of the electricity when of sufficient intensity, and not the 

 necessary consequence of its passage. 



A similar experiment having been tried with phosphorus 

 melted under spirits of wine, (being a non-conductor,) it was 

 found to obey the same law with water; that is, to convey the 

 current through its substancef. 



To determine whether the metals followed the same law, I 

 suspended from the top of the new patent shot tower at Wa- 



* Series VIII. (970.) 



f It was unnecessary to try similar experiments with the analogous 

 bodies, sulphur, selenium, and iodine. 



