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diffufion be communicated both to the bodies and to the inter- 

 mediate fpace ; but no reafon appears, which would induce us to 

 fuppofe that the bodies themfelves (hould recede to a greater 

 diftance. M. De Luc does indeed endeavour to prove that fuch 

 a motion fhould take place, but by an experiment whofe folution 

 contradidls his own theory. He fufpended by a filk thread a large, 

 but light, metallic ball, and prefented it in a ftate of pofitive elec- 

 tricity to a body negatively eledrified. The former was attracted 

 towards the latter until it arrived at a certain diftance, at which 

 it difcharged its eledricity. Hence he concluded, in general, that 

 when a body has more of the eledric fluid than the neighbouring 

 bodies, and is lefs difpofed to refift its own motion than to abandon 

 the excefs of its eledric matter, it will move towards that place 

 which contains lefs of this matter. But in this experiment he con- 

 fiders the two bodies as ading on each other at a diftance without 

 any reference to the intermediate air. 



Mr. Cavallo*, in the laft edition of his treatife on eledricity, 

 has obferved, that the mutual repulfion of two bodies negatively 

 eledrified is ftill fuppofed to contradid the theory of Franklin; 

 and has therefore deemed it necefl"ary to obviate the objedion by 

 a very particular detail. For this purpofe he has premifed the 

 following propofitions. Prop. i. No eledricity can appear on the 

 furface of a body, or no body can be eledrified either pofitively or 



negatively, 



* Vol. III. p. 192. 



