1881.] 



On the Refraction of Electricity. 



437 



Many questions have occurred to me in the investigation of which 

 this method might be expected to afford material assistance. But the 

 one of immediate attraction was whether electricity is endowed, like 

 light, heat, and sound, with the quality of refraction. From the 

 general resemblance of the fundamental laws of the forms of energy, I 

 instituted experiments in the expectation of finding an answer in the 

 affirmative to this question, the better conducting electrolytic medium 

 being taken as the electric analogue of the more rare medium in> 

 light. 



Refraction. 



My first trials were made with double convex-shaped bladders. 

 These gave what I took to be a slight evidence of refraction, though 

 the result was far from satisfactory. Triangular-shaped cells were 

 next employed, made by placing diaphragms of parchment-paper 

 obliquely across the electrolytic cell near its ends. In this way unmis- 

 takeable proof was obtained of the bending of the energy in passing* 

 the line of demarcation of the two media. When the influence passed 

 from one medium to the other perpendicularly, i.e., when the dia- 

 phragms were parallel to the plane of the electrodes, no refraction 

 whatever took place. 



On further consideration the arrangement which appeared less open 

 to objection, and at the same time the most simple and theoretically 

 the best, was a refracting cell, having parallel sides of some material 

 permeable to the electric influence. In the first instance parchment- 

 paper was the material employed. Two sheets of this substance were 

 fixed in a vertical position across an electrolytic cell, 380 millims. long r 

 128 millims. broad, and 128 millims. deep, at an angle of 45°. They 

 were parallel to one another, 76 millims. apart, but equidistant from 

 the respective ends of the cell. 



An unit current was employed, and copper electrodes of the breadth 

 and depth of the outer or transmitting cell. A 1 per cent, solution of 

 copper sulphate was placed in the inner or refracting cell, and a con- 

 centrated solution of the same salt in the transmitting cell. On placing 

 successive analysers* lengthwise in several parts of the central line 

 joining the electrodes, parallel distributions were recorded by all the 

 plates in the transmitting cell, but the one in the refracting cell 

 recorded a non-parallel distribution of a most pronounced character, 

 and it was evident from the degree of curvature of the ions that the 

 course of the energy on passing into the medium of less conductivity, 

 had bent out of its original course some 20°. 



The difficulty of keeping the parchment diaphragms as rigid as was 

 necessary for a more extended study of this phenomenon of refraction 



* Unless the contrary is stated, it is to be understood that analysers 40 x T 

 millims. were vised, and placed in the electrolyte with their shorter edges upright. 



