'12 HISTORY Of GALVANISM. 



an apparatus may be conftrucled of one metal and charcoal, of 



one metal alone, or even of charcoal alone, provided a proper 



and Divy's ex- fluid be interpofed to each fur face. The experiment related 



gafeTi^fepar^c h >' Mr * Dav y> where ' ll P on uniting the ends of the pile to two 



veflcls. glatFes of water by means of mufcular fibres, while the glades 



themfelves were connected by a filver wire, the effects of the 



ends of the wire were reveifed, admits of a fimple folution. 



The fluid mutt have been conducted along the fibres folely in 



confequence of the moifture attached to 'hem; when it left 



the plus end of the pile it would therefore decompofe part of 



this water, and pafs along in union with'kidrogcn to the filver 



wire, where the hidro^en would be difengaged. The other 



end of the filver will then become oxidated, and the hidrogen 



abforbed will be evolved at the minus end of the pile. 



Fourcroy and I have protracted this communication to fo unufual a length, 



Thenard's expe- ^ j & jj , ^ additional remark with retped to the 



riment that the , r • • • 



power of giving fact firft afcertained by Fourcroy, that the power of the pile in 



fliccks and giving (bocks is not proportionate to its power in confuming 

 burning wire de- & *6 t" t I 6 



pend on the mode metals. A few alternations or large plates are more powertul 

 of building the j n effecting the latter operation, while the fame quantity of 

 metal employed in conftructing a higher pile of Iefs diameter, 



referred to elec- affords a more powerful fliock. It appears from every cir- 

 trical phenomena ft th fc ^ force f ^ g^ depends almo ft ent \ re \ y 



exhibiting the ' . . ] f y 



fame refult with upon the concentration of the electric fluid ; the lame quantity 



coated jars. which, when contained in a few jars highly charged, would be 

 fuffkient to deftroy animal life, ifdifperfed over 100 jars would 

 be fcarcely perceptible. On the other hand, in the combuftion 

 of metals the abfolute quantity of electricity is of great impor- 

 tance; provided the current be rapid (which, from the experi- 

 ments of Dr. Van Marum, appears to be the cafe with the pile 

 of Volta in an amazing degree), and if the quantity of fluid be 

 confiderable, its ftate of intensity is of lefs moment f. The in- 

 telligent reader wilJ at once perceive in what way the fact ob- 

 served by Fourcroy admits of explanation from this train of rea- 

 soning. 



* Cuthbertfon firft obferved in a letter to me (1793) the ftriking 

 .fact, that the combuftion of equal lengths of the fame wire is made 

 by equal quantities of electricity, whether the intenfity be greater or 

 Jefs (within certain extended limits). See Account of Experiments. 

 Philof. Journal, quarto, II. 215. Auguft, 1798.— N. 



2 III. On 



