t^t Experiments in EUclriciiy 



repetitions of the conta6l were required to bring the charge 

 ot the battery to that degree of intenlity which the pile com- 

 municated at one. 



They were of opinion that the fenfation of the difcharge 

 difl'ered nothing at equal intenfuies, whether the battery were 

 charged by the pile or the plate apparatus. In Hiort, they 

 confider the two as mere exciters of the fame eleifriclty ; and 

 confequently, that the hippofed galvanic Ihiid has no exiftence 

 diftinil therefrom. 



Van Marum obferves, that the rapidity of the current of 

 ele<?tricitv in tlie pile nrafl be inconceivable, fince, by a con- 

 tact lafting only i-2oth of a fecond, it will charge com- 

 pletely 137 fquare feet of furface ; an ffle£f exceeding, in his 

 opinion, the power of every known ele<Slrical apparatus, ex- 

 cept the laree one in the Tevlerian mufaeum ! 



This pile was verv carclully inlulateJ. on a plate of gum 

 lac, and fupported in its vertical pofiiion bv flicks of fcaling- 

 wax. Cloth foaked in folution of muriate of ammoniac was 

 ufed to feparaie the pairs of metals. 



Thev conflru(Sted a fecond pile with 5-inch fquare plates 

 of copper and zinc. 7'his proved much more powerful when 

 arranged in -52 pairs perpendicularly, than vvhen, by laying 

 down four pieces in conta6t at once, the height was reduced to 

 ■ eight pairs, and the furface in each quadrupled. The former 

 pile melted five inches of No. \6. (iron wire) into globules, 

 and reddened feven inches. In attempting to carry it higher, 

 the weight of the fupcrior part, expreffing the liquid from the 

 inferior, deflroyed the efib6t. They remedied this by cou- 

 nectmg four (hort piles, and thus obtained the joint action 

 of no pairs of the latter metals. 



In order to determine whether there exifls any perceptible 

 difference between the fpark given by the pile to any conduct- 

 ing body, and that which it receives therefrom, " we em- 

 ploved (favs Van Marum) a bowl of quickfilver fuitably con- 

 neded bv a wire with the funerior plate of one of the outfide 

 piles, and we brought to its furface one while the point of 

 a needle attached to the wi-re of communication, then the - 

 bluntei point of the latter. We next connected tiic quick- 

 filver with th'j other extremity of the piles, and, >cpeating 

 thi-; feveral limes, we could fee, in one inftance, the fpark 

 pafs from the conducting wire into the quickfilver, in the 

 other from the quickfilver to the wire." The refult fatk^ficd 

 them, that there is not the lead perceptible difference be- 

 tween the pofitive and the negative fparks : but this trouble 

 was compenfated by the view of a very beautiful and interefting 

 pha-nomenon. " When we touched (fays Van Marum) x\\^ 

 4 fuiface 



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