J8S ELECTRICITIES DISTINGUISHED. 



IX. 



An Etfcfl hitherto unpublijlied, by ivhich the two Electricities are 

 dijtinguijhed. In a Letter from Mr. John Cuthbertson. 



To Mr. NICHOLSON, 

 Dear Sir, 



Letter. vJN reading your note refpecting the iuuTuments by which 



the two kinds of electricity are diftinguiflied, or its direction 

 afcertained, it brought to my mind an experiment which I 

 made with that view in the year 1777 in Holland ; I believe 

 it is not known here, fo perhaps you may think it worthy of a 

 place in your valuable Journal, 



I am, 



Dear SIR, 



your's refpectfully, 



J. CUTHBERTSON. 



Poland Street, Soho, OB. 19, 1802. 



Experiment. A INSULATE two wires furniflied at each end with a metal 

 t^baHs^the ^ of a k° ut i °f an incn diameter, connect one with the pofi- 

 oppofite ftates of tive conductor, and the other with the negative conductor of 



its flame* u*h an e ^ e< ^ rical macnine J ^ et tnem f° that their balls may be at 

 agitated, and about four inches diftance, place between them a common 

 heats the nega- fized lighted candle, with the center of its flame nearly upon 

 a level with the centers, and at an equal diftance from each ; 

 if the machine be put in motion the flame will waver very 

 much, and feems rather more to incline to the negative ball 

 than to the poiitive one, but is very equivocal : continue turn- 

 ing (if. the machine be a plate of two feet diameter) about 50 

 revolutions, then the negative ball will begin to grow warm, 

 and the pofitive ball remain cold ; if the revolutions be multi- 

 plied to 200, the negative ball will be too hot to be touched, 

 and the pofitive remain as cold as at the beginning. 



X. Palpable 



