332 M. Edmond Becquerel in Reply to Mr. Daniell. 



pile, although very convenient, as based upon the same prin- 

 ciples as the apparatus which my father has used for a long 

 time. 



Further on Mr. Daniell adds : " Even in the use of the 

 diaphragm, which might at first sight appear similar, there is 

 a direct opposition, for my object is to keep the two electro- 

 lytes which I employ perfectly separate, so that no portion 

 of one may penetrate to the other, except in the process of 

 electrolysis." 



I confess that I know not how Mr. Daniell can separate 

 two liquids by a membrane moistened by them and which 

 they can penetrate, without that passage from one to the other 

 taking place which is otherwise called endosmose and exos- 

 mose. It is impossible to realize this condition; the only 

 means of retarding for as long a time as possible the mixture 

 of the two liquids, is by substituting for the membrane a thick 

 diaphragm of clay, as did my father; the intensity of the cur- 

 rent is then diminished, but constant effects are obtained 

 which may continue for months, for years. 



Still further on Mr. Daniell says : " and I repeat, that in 

 my constant battery nothing depends upon the contact and 

 action of the two liquids upon each other." 



I do not understand this assertion; for every one knows that 

 two different liquids acting upon each other by an intermedial 

 membrane, disengage electricity enough to produce a current ; 

 and if Mr. Daniell wishes to convince himself of it, he has 

 only to take away, in one of his couples, the plate of zinc and 

 that of copper, and to substitute two plates of platina for them ; 

 he will have a current owing to the reaction of the two liquids 

 upon each other, less intense indeed than that obtained with 

 a couple in which an oxidable metal is included. 



Mr. Daniell also says, that " the amount of force obtained 

 by my father's apparatus is insignificant with regard to its ap- 

 plication to the arts." 



I will reply yes and no to him; yes, if there is a question 

 of apparatus like those of Mr. Daniell, designed to obtain cur- 

 rents which are to be transmitted into liquids placed in se- 

 parate vessels; no, if the currents are to react chemically on 

 the liquids making a part of the apparatus themselves. 



In short, the apparatus constructed by my father, six years 

 ago, for the treatment of ores of silver of lead and of copper, 

 are based on the same principles whioh I have before ex- 

 plained, and are of much more considerable dimensions than 

 those of Mr. Daniell, since each couple requires 1000 litres 

 of liquid to act, and six similar couples have been united, 

 so that 6000 litres have acted at the same time, and the 



