300 Prof. Daniell on the Constant Voltaic Battery. 



" II faut que les metaux qui composent chaque couple plon- 

 gent clans des liquides differents, separes par une membrane 

 ou un diaphragm capable de laisser traveiser pen a pen les li- 

 quides, cette disposition etant la seule par laquelle le courant 

 secondaire produit par la polarization des electrodes puisse 

 etre detruit." (P. 442.) 



M. E. Becquerel, however, allows that even this apparatus, 

 which so completely solves the problem of the constant battery, 

 is incapable of application. 



"Ce dernier appareil resout completement la question sous 

 le point de vue scienlifique, mais potir les applications le cou- 

 rant electrique n'aurait pas une energie suffisante, car alors 

 il faudrait de plus grands elements et en plus grand nombre, 

 ce qui serait assez couteux." 



He adds, " il s'ensuit que ces appareils, qui forment pile, 

 ont une intensite d'action constante pendant un temps consi- 

 derable : cette condition n'est remplie que quand V action est tres 

 lente." (P. 442.) 



It is difficult, indeed, to conceive that M. E. Becquerel can 

 be serious in attempting to trace an analogy between this ar- 

 rangement, or any of the similar apparatus formed of " tubes 

 en U," which his father has so successfully applied to the in- 

 vestigation "des actions lentes" and "the constant battery," 

 whose object is the generation of voltaic power, with a con- 

 stancy and rapidity which promises to render it applicable 

 not only to manufacturing but mechanical purposes. 



The very source of the current in the " chaine simple a oxy- 

 gene " is different from that of " the constant battery." M. 

 Becquerel, in his Traite de VElectricite (tome iii. § 526), 

 ascribes it to the slow and direct combination of the acid and 

 alkali ; but this explanation will not be deemed satisfactory, 

 since Dr. Faraday has shown that the decomposition and po- 

 larization of the molecules of an electrolyte are essential to the 

 establishment of a current. I have myself suggested an ex- 

 planation of the undoubted pheenomena of current and decom- 

 position which take place, which is quite compatible with these 

 conditions (Phil. Trans. 1840, p. 223). The origin of the 

 force is however, doubtless, to be found at the point of con- 

 tact of the two liquids, and not at the electrodes ; and I repeat, 

 that in my " constant battery " nothing depends upon the 

 contact and action of the two liquids upon each other. 



The amount of force is also perfectly insignificant with re- 

 gard to its application to the arts. It would be difficult to 

 obtain by this arrangement a decomposition amounting to 

 yi^th of a cubic inch of hydrogen and oxygen per minute, 

 while with a constant battery of my construction it is easy to 



