Prof. Daniell on the Con&tant Voltaic Battery. 295 



pense qu'il peut etre utile de presenter succinctement I'expose 

 de toutes les recherches qui ont ete faites pour obtenir des 

 piles dont Taction soit constante pendant un certain temps." 

 \Ann. de Chimie, tome iii. p. 436.) 



In this opinion I perfectly concur ; and it is for the purpose 

 of rendering such an account more perfect that I desire to 

 correct some misconceptions into which M. E. Becquerel has 

 fallen, and which have the effect of greatly mystifying the ori- 

 gin of constant batteries. After stating the well-known de- 

 fects of voltaic batteries of the common construction, in which 

 the two metals are plunged into the liquid in the same cell ; 

 and the necessity of constructing batteries of constant action 

 before they could be usefully employed in the arts, he pro- 

 ceeds to make the following comprehensive claim : — 



" C'est mon pere qui a donne le premier les principes sur 

 lesquels est fondee la construction de ces piles et qua forme 

 les premiers piles de ce genre." {Ann. de Chim, p. 437.) 



Now as I have claimed to be the inventor of " the constant 

 battery" (which was so named by myself), and as the Coun- 

 cil of the Royal Society have so far sanctioned this claim as 

 to award me the Copley Medal for my invention ; and as I 

 have most undoubtedly worked out the principles of its con- 

 struction by experiments and legitimate induction without the 

 slightest suspicion that M. Becquerel had preceded me in the 

 investigation, I was naturally very anxious to examine the evi- 

 dence upon which this assertion is founded. 



Previously to stating this evidence, M. E. Becquerel makes 

 some remarks upon the phsenomenon which has been most 

 inappropriately termed the -polarization of the plates of a vol- 

 taic battery, of which his lather, he observes, has given the 

 simple explanation. 



"Dans le passage d'un courant electrique a travers un li- 

 quide conducteur voici ce qui a lieu : quand le courant pri- 

 mitif traverse le liquide conducteur, des elemens acides sont 

 transportes au pole positif, et des elemens alcalins au pole 

 negatif; alors, en interrompant la communication entre les 

 lames decomposantes (ou electrodes) et la pile, les deux lames 

 se comportent vis-a-vis Tune de I'autre comme deux lames 

 que Ton aurait plongces, Tune dans un faible dissolution al- 

 caline, Tautre dans une faible dissolution acide : c'est-a-dire, 

 qu'en les mettant en relation avec un multiplicateur, il y aura 

 production d'un courant electrique du a la reaction des mole- 

 cules acides ou se comportant comme telles, sur les molecules 

 alcalines par Tintermediaire du liquide: ce courant sera par 

 consequent dirige en sens inverse du courant initial. Cet eflet 

 Be nianifeste toujours lorsqu'un courant traverse un liquide 



