ELECTRICITY, 85 



discharge, and not by a conduction similar to that which takes 

 place either with metals or with electrolytes. 



The ordinary attractions and repulsions of electrified 

 bodies present no more difficulty when regarded as being pro- 

 duced by a change in the state or relations of the matter 

 affected, than do the attractions of the earth by the sun, or. of 

 a leaden ball by the earth ; the hypothesis of a fluid is not 

 considered necessary for the latter, and need not be so for the 

 former class of phenomena. How the phenomena are produced 

 to which the term attraction is applied is still a mystery. 

 Newton, speaking of it, says : < What I call attraction may be 

 performed by impulse, or by some other means unknown to 

 me. I use that word here to signify only in general any 

 force by which bodies tend towards one another, whatsoever 

 be the cause.' If we suppose a fluid to act in attractions and 

 repulsions, the imponderable fluid must drag or push the 

 matter with it : thus when we feel a stream of air rushing 

 from an electrified metallic point, each molecule of air con- 

 tiguous to the point being repelled, another takes its place, 

 which is in its turn repelled ; how -does a hypothetic fluid 

 assist us here ? If we say the electrical fluid repels itself, or 

 the same electricity repels itself, we must go farther and assert, 

 that it not only repels itself, but either communicates its 

 repulsive force to the particles of the air, or carries with it the 

 particle of air in its passage. Is it not more easy to assume 

 that the particle of air is in such a state that the ordinary 

 forces which keep it in equilibrium are disturbed by the 

 electrical force, or force in a definite direction communicated 

 to it, and that thus each particle jn turn recedes from the 

 point ? As this latter force is increased, not only does the 

 particle of air which was contiguous to the metallic point re- 

 cede, but the cohesion of the extreme particles of metal may 

 be overcome to such an extent that these are detached, and 

 the brush or spark may consist wholly or in part of minute 

 particles of the metal itself thrown off. Of this there is some 

 evidence, though the point can hardly be considered as proved. 

 A similar effect undoubtedly takes place with voltaic elec- 

 tricity, acting upon a terminal immersed in a liquid ; thus if 

 metallic terminals of a powerful voltaic battery be immersed 



