32 



GALVANISM. 



itself be in a negative state with relation 

 to the zinc. If either of these states be 

 reduced to a more neutral condition by 

 communication with other bodies ; that 

 is, if the redundant electricity of the 

 zinc be carried off, and the deficiency 

 of electricity in the copper be supplied 

 from other sources, the electromotive 

 force will, he conceived, immediately 

 renew this difference 6f condition, and 

 thus maintain a continual and rapid 

 current of electric fluid, flowing always 

 in the same direction. 



(Ill .) It was further assumed in this 

 theory that liquids have no electromo- 

 tive power when in contact with metals : 

 and that this negative property enabled 

 them to transmit the electricity evolved 

 by the contact of the zinc and copper, 

 and which is accumulated in the zinc, 

 back again to the copper ; whence it is 

 again transferred to the zinc ; and so on 

 in a perpetual circle. In compound 

 galvanic circles, the electromotive force 

 residing in the surfaces of contact be- 

 tween the two metals in each pair of 

 plates, are all tending in the same direc- 

 tion ; and the several impulses they 

 give to the electricity conspire together 

 to increase the effect, which will there- 

 fore be the sum of all the forces taken 

 separately. Thus will a continued and 

 powerful stream of electricity be deter- 

 mined from the negative to the positive 

 pole of the battery, ready to circulate 

 through any conducting line of com- 

 munication extending between the two 

 poles. The office of the fluid is consi- 

 dered, in this theory, as simply that of 

 conducting the electricity from the one 

 metal to the other : its chemical action 

 on either of these being regarded as a 

 mere accidental circumstance, not in 

 any way concerned in the production of 

 galvanic or electrical effects. The effec- 

 tive quantity of electricity which actually 

 circulates in the voltaic battery is sup- 

 posed to be determined altogether by 

 the degree of conducting power possessed 

 by the liquid : for it is assumed that 

 the quantity which the electromotive 

 force existing at even the smallest sur- 

 face of contact between dissimilar me- 

 tals could set in motion, if the move- 

 ments of that electricity were not 

 impeded by the difficulty of its trans- 

 mission through fluids, would be incom- 

 parably greater than that which any 

 conducting fluid can discharge. 



(112.) Such is the general outline of 

 the electric theory, which it is scarcely 

 necessary to pursue in its various appli- 



cations, because there are several 

 facts which appear so totally at variance 

 with the immediate consequences of its 

 fundamental hypothesis, as to warrant 

 us in rejecting it. Chemical action be- 

 tween some of the elements of a galvanic 

 combination is so invariably connected 

 with the production of electrical effects, 

 that it would be a violation of all just 

 rules of philosophy not to consider these 

 two classes of phenomena as standing 

 to each other in the relation of cause 

 and effect. The quantity of galvanic 

 effect is always in proportion to the 

 energy of the chemical action. The 

 extent of contact between the two me- 

 tals, on the other hand, appears to 

 have no relation to the quantity of elec- 

 tricity which is developed. Combina- 

 tions producing galvanic effects may be 

 formed, as we have seen, with a single 

 metal only, when two fluids are present ; 

 and indeed, on other occasions, without 

 the presence of any metallic substance 

 whatever. We have also seen that the 

 same metals do not in all cases stand in 

 the same invariable electrical relation 

 to each other ; but that this relation is 

 determined by the chemical properties 

 of the; fluid with which they are placed 

 in contact. ( 75.) All these facts are 

 irreconcilable with the electric theory. 



(113.) Were any further reasoning 

 necessary to overthrow it, a forcible 

 argument might be drawn from the 

 following consideration. If there could 

 exist a power having the property 

 ascribed to it by the hypothesis, 

 namely, that of giving continual im- 

 pulse to a fluid in one constant direction, 

 without being exhausted by its own 

 action, it would differ essentially from 

 all the other known powers in nature. 

 All the powers and sources of motion, 

 with the operation of which we are 

 acquainted, when producing their pecu- 

 liar effects, are expended in the same 

 proportion as those effects ate pro- 

 duced; and hence arises the impossi- 

 bility of obtaining by their agency a 

 perpetual effect ; or, in other words, a 

 perpetual motion. But the electro-mo- 

 tive force ascribed by Volta to the me- 

 tals when in contact, is a force which 

 as long as a free course is allowed to 

 the electricity it sets in motion, is never 

 expended, and continues to be exerted 

 with undiminished power, in the produc- 

 tion of a never-ceasing effect. Against 

 the truth of such a supposition, the pro- , 

 babilities are all but infinite. 



