ELECTRICITY. 81 



phorus in the vacuum of a good air-pump, a deposit of allo- 

 tropic phosphorus soon coats the interior of the receiver, 

 showing an analogous change to that produced in oxygen ; 

 and in this case a series of transverse bands or stratifications 

 appear in the discharge, showing a most striking alteration 

 in its physical character, dependent on the medium across 

 which it is transmitted. These effects were first observed by 

 me in the year 1852. They have since been much examined 

 by Continental philosophers, and much extended by Mr. 

 Gassiot ; but no entirely satisfactory rationale of them has yet 

 been given. 



There are many gases which either do not show any per- 

 manent change, or (which is more probably the case) the 

 changes produced in them by the electrical discharge have 

 not yet been detected. Even with these gases, however, the 

 difference of colour, of length, or of the different position of a 

 certain dark space or spaces which appear in the discharge, 

 shows that the discharge differs for different media. We never 

 find that the discharge has itself added to or subtracted from 

 the total weight of the substances acted on : we find no evi- 

 dence of a fluid but the visible phenomena themselves ; and 

 those we may account for by the change which takes place in 

 the matter affected. 



I have here, as elsewhere, used words of common accepta- 

 tion, such as ' matter affected by the discharge/ &c., though, 

 upon the view I am suggesting, the discharge is itself this 

 affection of matter ; and the writing these passages affords, 

 to me at least, a striking instance of how much ideas are 

 bound up in words, when, to express a view differing from 

 the received one, words involving the received one are neces- 

 sarily used. 



I pass now to the effect of the transmission of electricity 

 by the class of the best conducting bodies, such as the metals 

 and carbon ; here, though we cannot at present give the exact 

 character of the motion impressed upon the particles, there 

 are yet many experiments which show that a change takes 

 place in such substances when they are affected by electricity. 



Let discharges from a Leyden jar or battery be passed 

 through a platinum wire, too thick to be fused by the dis- 



G 



