218 On Wave-Theories of Lights Heat^ and Electricity . 



their associated egther the principle of elasticity, or of that re- 

 pulsive force which equilibrates the attractions of molecules or 

 atoms inter se. 



With regard to Boscovich^s theory of alternations of attraction 

 and repulsion between particles themselves at minute distances, 

 I reject it as irreconcilable with the phenomena, inasmuch as at 

 any temperature a body resists either compression or extension ; 

 so that its actual state must result from an equilibrium of two 

 opposing forces, viz., on the one hand, the mutual attraction of 

 the molecules (which even with gases must be allowed to exist 

 at whatever distance, inasmuch as gravity has no known limit, 

 and the attraction which our earth exercises over gases at their 

 extreme rarefaction is an undoubted fact), and, on the other hand, 

 the self-repulsion of the eether associated with the molecules, 

 which may thus (in chemical philosophy) take the place of the 

 " caloric ^' of former times. 



In accordance with these views, electricity should be looked on 

 in future (in chemical theories) as causing decomposition by se- 

 parating combined molecules, and thus allowing the action of 

 various forces of attraction to play their allotted parts in the 

 changes which take place. 



The views of the illustrious Faraday on this subject appear to 

 have varied much from time to time : although he admits that 

 chemical combination alone never eliminated electricity, and that 

 " decomposition ^^ was an essential in voltaic arrangem.ents, still, 

 on the whole, his leaning appears to have been to the views of 

 Davy, ^'that electricity was the cause (not the opponent) of che- 

 mical affinity" (Researches, 858-861). 



With respect to electrical phenomena, it appears to me that 

 there are " waves of translation " as well as waves of vibration, 

 the former being always productive of the latter, and the prin- 

 cipal agents, as such, in dynamic electricity. The "parallelism •'■' 

 of the quality of conductivity in bodies (for temperature and for 

 electricity) corroborates the view I have taken of the intimate 

 connexion of the motions of molecules with those of their asso- 

 ciated sether — the former sluggish and persistent, the latter 

 amazingly rapid and evanescent, while both present the same 

 relative velocities in passing through the same substance^. 



In conclusion I would submit that many erroneous theories 

 appear to have arisen from regarding the ultimate particles of 

 a body as spheres. They might be spheroids or ellipsoids ; or 

 more probably they may have the smjoZes^ forms of those crystals 

 which they build up by their mutual aggregation ; but taking 

 into account the polar forces which come into play at insensible 



* Dessaignes first observed that "6ac? conductors of electricity are easily 

 rendered phosphorescent, good conductors rarely, if ever." 



