90 DR. FARADAY'S EXPERIMENTAL RESEARCHES IN ELECTRICITY. (SERIES XII.) 



contiguous particles obedient to one common law, as a very important result ; and, 

 on the other hand, the identity of character which the two acquire when viewed by 

 the theory (1326.), is additional presumptive proof in favour of the correctness of 

 the latter. 



1339. That heat has great influence over simple conduction is well known (445.), 

 its effect being, in some cases, almost an entire change of the characters of the 

 body (432. 1340.). Harris has, however, shown that it in no respect aff^ects gaseous 

 bodies, or at least air* ; and Davy has taught us that, as a class, metals have their 

 conducting power diminished by it-f-. 



1340. I formerly described a substance, sulphuret of silver, whose conducting 

 power was increased by heat (433. 437. 438.) ; and I have since then met with an- 

 other as strongly affected in the same way : this is fluoride of lead. When a piece of 

 that substance, which had been fused and cooled, was introduced into the circuit of 

 a voltaic battery, it stopped the current. Being heated, it acquired conducting powers 

 before it was visibly red hot in daylight ; and even sparks could be taken against it 

 whilst still solid. The current alone then raised its temperature (as in the case of 

 sulphuret of silver) until it fused, after which it seemed to conduct as well as the 

 metallic vessel containing it ; for whether the wire used to complete the circuit touched 

 the fused fluoride only, or was in contact with the platina on which it was supported, 

 no sensible difference in the current was observed. During all the time there was 

 scarcely a trace of decomposing action on the fluoride, and what did occur, seemed 

 referable to the air and moisture of the atmosphere, and not to electrolytic action. 



1341. I have now very little doubt that periodide of mercury (414. 448. 691.) is a 

 case of the same kind, and also corrosive sublimate (692.). I am also inclined to 

 think, since making the above experiments, that the anomalous action of the prot- 

 oxide of antimony, formerly observed and described (693. 801.), may be referred in 

 part to the same cause. 



1342. I have no intention at present of going into the particular relation of heat 

 and electricity, but we may hope hereafter to discover by experiment the law which 

 probably holds together all the above effects with those of the evolution and the dis- 

 appearance of heat by the current, and the striking and beautiful results of thermo- 

 electricity, in one common bond. 



^ viii. Electrolytic discharge. 



1343. I have already expressed in a former paper (1164.) the view by which I hope 

 to associate ordinary induction and electrolyzation. Under that view, the discharg:e 

 of electric forces by electrolyzation is rather an effect superadded, in a certain class 



* Philosophical Transactions, 1834, p. 230. t Ibid. 1821, p. 431. 



