5^ MR. CUTIfPEaTSON ON ELECTRICITY, i 



XIII. 



Letter from Mr, Cuthbertson, containing Remarks on Mr^ 

 Wm. Wilson's and Mr, Hauy's Experiments on the Eleo* 

 tricity of Metals. 



To Mr, NICHOLSON, 



london, 54, Poland- Street, 

 Dear Sir, April2'^, 1805, 



Mr, Wilfon's 1N your valuable Journal for January, page 42, you have 

 experiments on favoured us with a letter from Mr. Wiifon, containing fome 

 experiments which he calls, exhibiting the eleBricity of metals. 

 of copper fiftcd Mr. Wilfon fays in his table of experiments, that copper 

 through tine, ^jj^g^ ^j^j^j through zinc is pofitively elearified ; this is an 

 error which I thought myfelf obliged to take notice of, as it 

 is a direfl contradidion to what I have alTerted in viy examina^ 

 tion of Sig, Volta's experiments^ xvhich he calls funda?nental, and 

 on which his theory of galvanifm refis; fee this Journal, vol, II. 

 controverted page 281 ; I have fald therein, that if a plate of zinc befepa- 

 e jmen't^of con- ^^.ted from a copper one, it will be positive, confequently 

 taft and fepara- leave the copper negative if infulated ; whether this experi- 

 ^'°"* ment be performed as I have therein mentioned, or according 



to Mr. Wilfon, the one reduced into filings, and afterwards 

 fifted through holes made in the other metal, the eledricity 

 excited muft fall under the fame denomination, the difference 

 will be that the quantity of eleflricity excited will be more by 

 Mr, W.*s method than mine, becaufe he hais multiplied the fe-, 

 parations, a fad well worth notice. 

 Contaft and Mr. W.'s chief objeft in view feemingly, is to prove that 



ftparation pro-^ jj^g feparation of metals is the caufe of the eleclric fluid beiner 

 diice the cleftnc . , , . . t • . ,- 



ftatc; excited and not touching. I cannot perceive that thefe ex- 



periments throw any light upon that fubje(5tj, as both touching 

 and feparating are here employed, 

 kut neither ad In my fec^^nd volume on eledriclty, publiflied in Amfier, 

 will do alone. ^.^^^ jj„„q 1782, I have proved by experiment that neither 

 touching nor fviciion feparately employed excites ele6^ric fluid, 

 frjd^ion and feparating jointly employed, is a powerful exciter 

 of eledricity on glafs; touching and feparating jointly em- 

 ployed on glafs excite eleflric fluid in a flight degree, anc| 

 only when the (late of tjie atmofphere is favourable. 



