Obfervations en the Theory of EUBric AttraBion. 461 



■V. • 



Obfervations on the Theory of EleHric Attra3ir,n and Ripuljion. By the Rev, George 



Miller. F. T. C. D.* 



B> 



► EFORE that the theory of a fingle eleftric fluid was propofed, no difficulty occurred 

 in the explanation of the attraftions and repulfions obferved to arife from eleftricit.y. If we 

 admit that there are two diftinft eleftric fluids, each of which flrongly attrafts the other, 

 but confifts of particles mutually repulfive ; it becomes eafy to account for the attraftion 

 fubfifting between bodies in difFerent flates of eleftricity, and the repulfion between thofe 

 in the fame. But when Dr. Franklin f, obferving that a man, flanding upon a non-con- 

 dudtor, could not eledlrify himfclf, but that he could electrify another perfon alfo ftanding 

 upon a non-condu£tor, was induced to regard the operation of exciting eleflricity only as a 

 transfer of one and the fame fluid .from one body to another; it was found to be difficult 

 to reconcile to the new theory the mutual repulfion of bodies in that ftate which is, ac- 

 cording to this theory, denominated negative eleftiicity. Dr. Franklin :J: acknowledged 

 that he could not affign a fatisfattory reafon for it ; and Dr. Prieftley § has propofed it, 

 as one of the queries remaining to be folved for completing the fcience of ele£lricity. 

 Many attempts have been made to obviate this apparent objection to the fimple theory of a 

 fingle fluid ; but the difficulty feems ftiU to be as great as it was in the. time of Franklin, 



II ^pinus has applied a very elaborate fyftem of mathematical reafoning to the folution 

 of eleftrical phsenomena, and has adopted as the bafis of his theory, the fame opinion 

 which Franklin had entertained concerning the nature of the eleftric fluid ; but he has 

 combined with this opinion other principles fo inadmiffible, that his reafonings cannot be 

 regarded as juft explications of the phxnomena. He has aflumed, apparently without any 

 other reafon than its importance to his conclufion, that the particles of all other fubftanccs 

 repel each other. His fyftem muft therefore be confidered, not as a phyfical folution 

 agreeable to the known laws of natural operations, but merely as an ingenious exercife of 

 mathematical ability. 



M. De Luc, who rejefted the folutions of Spinas has endeavoured to fupply the defi- 

 ciency. ** Having remarked that the divergence of the balls of an eleftrometer, included 

 in the receiver of an air-pump, is continually diminifhed during the progrefs of exhauflion ; 

 he confiders it as proved, that the caufe of all ele£^rical movements, whether of attra£tion 

 or of repulfion, is the a£tion of the air. This principle he applies in the following manner. 

 When two bodies are in fimilar ftates of eledricity, either pofitive or negative, they will 



• Irifh Traiifaaions, VII. 139. + Dr. Prieftley's Hiftory of Eleftricity, p. 161, 



J Dr. Prieftley's Hiftory of Eleftricity, p. 1^5. § Ibid, f..^^^^, 



I Journal de Phyfique, D«c. 1787. •• Ibid. Juin 1790. 



confpir* 



