38 S lloyal Academy of Sciences of Paris. 



March 1st. — Mr, Brande on steel. 



March 8th. — Mr. Bray ley on the equilibrium of the atmosphere 

 as dependent on the united action of gravity and temperature. 



March 15th — Mr. Cowper on pottery. 



March '22nd. — Mr. Faraday on Airy's correction of the ship's com- 

 pass in an iron vessel. 



ROYAL ACADEMY OF SCIENCE.S OF PARIS. 

 April 15th. — A. paper " On a new Voltaic Combination," by W. 

 K. Grove, Esq., M.A., M.R.I., was communicated by M. Becquerel, 

 for a copy of which, as follows, we are indebted to the author. 



Mr. Porrett was, I believe, the fii-st who employed a bladder to 

 separate the liquids in the operating cell of the voltaic pile. M. 

 Becquerel, by introducing this into the exciting cells, has shown us 

 how to render constant the primitive intensity of the battery by 

 preventing cross precipitation* ; Mr. Daniell has remedied some 

 practical defects in M. Becquei'el's arrangement, and his form of bat- 

 tery is undoubtedly the best of any that have been hitherto proposedf. 



In a letter published in the Phil. Mag. for February, (p. 127) I en- 

 deavoured to show, that in addition to the immense benefit derived from 

 constancy of action, which was the object aimed at by these gentle- 

 men, the combination of four elements was capable of producing a much 

 more powerful development of electricity than that of three, as by 

 this means we have nearly the sum of chemical affinities instead of 

 their difference ; I also there suggested that if the principles I had 

 laid down were true, there was every probability of superior combi- 

 nations being discovered ; I have lately been fortunate enough to 

 hit upon a combination which I have no hesitation in pronouncing 

 much more powerful than any previously known. The experiments 

 which led to it are curious, and possess an interest of their own, as 

 they prove a well-known chemical phsenomenon to depend upon 

 electricity, and thus tighten the link which binds these two sciences. 

 The effect to whicia I allude is the dissolution of gold in nitro-muriatic 

 acid ; this metal, as is well known, not being attacked by either of 

 the acids singly. The following experiments leave, I tliink, no doubt 

 as to the rationale of this phsenomenon. 



1st. Into the bottom of a wine glass I cemented the bowl of a 

 tobacco pipe ; into this was poured pure nitric acid, while muriatic 

 acid was poured into the wine glass to the same level : in this latter 

 acid two strips of gold leaf were allowed to remain for an hour, at 

 the end of which time they remained as bright as when first im- 

 mersed. A gold wire was now made to touch the nitric acid and tlie 

 extremity of one of the strips of gold leaf ; this was instantly dis- 

 solved, while the other strip remained intact. 



2nd. The experiment was inverted, but offered some difficulty, as 

 the gold would not remain an equally long time in the nitric acid, 



* Ann. de Chimie, vol. xli. M. Becquerel, by employing another form of 

 diaphragm, that of moistened clay, has produced those results of electro-ciy- 

 stallization which are sogenefallv known. [See Scient. Mem. vol. i. p. 414.] 



t Phil. Trans. 183G. [Sec L. and E. Phil. Mag. vol. xii p. 350.] 



