142 DR. FARADAY'S EXPERIMENTAL RESEARCHES IN ELECTRICITY. (SERIES XIII.) 



guished and established, and another argument in favour of that molecular theory of 

 induction, which is at present under examination*. 



1561. What I have had to say regarding the disruptive discharge has extended to 

 some length, but I hope will be excused in consequence of the importance of the sub- 

 ject. Before concluding my remarks, I will again intimate in the form of a query, 

 whether we have not reason to consider the tension or retention and after discharge 

 in air or other insulating dielectrics, as the same thing with retardation and discharge 

 in a metal wire, differing only, but almost infinitely, in degree (1334. 1336.). In other 

 words, can we not, by a gradual chain of association, carry up discharge from its oc- 

 currence in air, through spermaceti and water, to solutions, and then on to chlorides, 

 oxides and metals, without any essential change in its character ; and at the same 

 time, connecting the insensible conduction of air, through muriatic acid gas and the 

 dark discharge, with the better conduction of spermaceti, water, and the all but 

 perfect conduction of the metals, associate the phenomena at both extremes ? and 

 may it not be, that the retardation and ignition of a wire are effects exactly corre- 

 spondent in their nature to the retention of charge and spark in air ? If so, here 

 again the two extremes in property amongst dielectrics will be found to be in inti- 

 mate relation, the whole difference probably depending upon the mode and degree in 

 whi6h their particles polarize under the influence of inductive actions (1338. 1603. 

 1610.). 



^ X. Convection ; or carrying discharge. 



1562. The last kind of discharge which I have to consider is that effected by the 

 motion of charged particles from place to place. It is apparently very different in 

 its nature to any of the former modes of discharge (1319.), but, as the result is the 

 same, may be of great importance in illustrating, not merely the nature of discharge 

 itself, but also of what we call the electric current. It often, as before observed, in 

 cases of brush and glow (1440. 1535.), joins its effect to that of disruptive discharge, 

 to complete the act of neutralization amongst the electric forces. 



1563. The particles which being charged, then travel, may be either of insulating 

 or conducting matter, large or small. The consideration in the first place of a large 

 particle of conducting matter may perhaps help our conceptions. 



1564. A copper boiler 3 feet in diameter was insulated and electrified, but so feebly, 

 that dissipation by brushes or disruptive discharge did not occur at its edges or pro- 

 jecting parts in a sensible degree. A brass ball, 2 inches in diameter, suspended by 



* I cannot resist referring here by a note to Biot's philosophical view of the nature of the light of the elec- 

 tric discharge, Annales de Chimie, liii. p. 321. 



