Experimmts and Ohfervatlons on the Galvanic Power. 43 



apparatus, which has the advantage of cheapnefs, and confiderable power, and would no 

 doubt anfwer very well, if a way could be difcovered for preventing the moifture from pene-. 

 trating through the pots, though I have not been able to effect it by any mode of coating 

 them : in cafe anybody fliould be inclined to try this method, I have annexed a drawing 

 of the manner in which the pots are connected, at the fame time obferving that the zinc 

 pieces ought to b6 foldered to the brafs wire. If ever Galvanifm can be applied to the 

 arts, by procuring alkali in an economical procefs, the above bids fairer to attain that end 

 than any thing I have yet met with, as the pots are in a fliort time covered with an effloref- 

 cence of foda when common fait is ufed, which might be colleded tolerably pure from 

 their outfides. 



In this range the zinc became the gafeous, and the plumbago the oxidating fide, which 

 fhows that it is as far beyond zinc, as zinc is beyond filver, in the arrangement of Galvanic 

 oxidating power, though there is no reafon to believe that the plumbago undergoes any 

 change itfelf. When connected with a bent fyphon, filled with diftilled water, by either 

 filver, brafs, or iron wires (even though the bend was filled with quickfilver), both fides 

 foon changed the reddened litmus paper to the purple, though the plumbago fide reftored 

 it to be a perfecSt blue; (howing that a much greater quantity of alkali was formed on that 

 fide than on the other. 



Tlie only apparently ele£tric phenomenon, independent of the fliock, that I could obferve 

 by this range, was that the powder of the plumbago aflumed the form of little liars on the 

 furface of the water, which fome people might be inclined to think proceeded from a (late 

 of pofitive ele6lricity. 



Having lately difcovered a mode of encreafing prodigloufly the powers of the pile, I have 

 laid afide the cumberfome and bulky apparatus of the range, and cannot recommend it for 

 any thing but its cheapnefs, and the poflibility of being fatisfied at a moderate expence, by 

 means of the larger fized crucibles, of the proportion that bulk or furface bear to alternated 

 numbers in Galvanic power. 



I alfo annex a drawing of the box, in which I enclofe ray pile, and which I can recom- 

 mend for convenience and portability ; the improvement that I have made in the pile is on 

 the matter by which the pieces are put together, to which I was led by theory. 



I took a pound of pipe clay, an ounce of plumbago powder, an ounce of black oxide of 

 manganefe, and two ounces of common fait, and made them into a pafte with water ; in the 

 ufe of clay I took advantage of the obfervations of Dr. Moyfe. 



This mixture gave 126 pairs of filver and zinc of the half-crown fize, a power beyond 

 any thing I have yet heard defcribed, and gave the fpark moft vividly, in a room where the 

 fun was fhining, either from a bit of common coak, or the point of a needle ; but even 

 when two pieces of metal were held in the hand, though perfeflly dry, and the wires 

 touched by them, a fliock was felt much greater than that procured from a very confiderable 

 number of pieces with the afliftance of moifture, fet up In the common way. When the 

 pile begins to weaken a little, if one of the wires is allowed to vibrate on the piece of metal 



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