1 16 On AttraBion and Repulfton. 



into a public aft of exorcifm ? This would not have paffed 

 even on the authors of the Malleus Maleficarutn, for they 

 required figns of fupernatural agency, fuch as the fufpen- 

 fion of the pofleffed in the air, without any vifible fupport, 

 or the ufe of different languages, unknown to the demoniac 

 in his natural ftate. 



Man/eruntf hodieque majtent 'veftigia ruris. 



Letter on Attraction and Repulsion ; com- 

 municated by Dr. Percival, OSlober ii, 1786. 



DEAR SIR, 



I SHALL think myfelf honoured by your 

 communication of the following experi- 

 ments and obfervations to the Manchefter Lite- 

 rary Society, if you think them worth their 

 attention. 



TFIE waving motion of oil and water con- 

 tained in a glafs fufpended and vibrated in 

 (Irings, may be accounted for without confider- 

 ing any repulfion or difference of gravity be- 

 tween the two fluids. To prove whether a 

 greater difference of fpecific weight would in- 

 creafe the motion, I tried quickfilver and water, 

 and found that in this cafe no waving motion 

 .was perceptible. I then tried milk and water, 



whofc 



