Mr. Grove on a Neta Voltaic Combination. 389 



from the effect of the nitrous gas ; enough, hoAvever, was ascer- 

 tained to prove that to the gold in this acid contact made little or 

 no difference ; while the gold in the muriatic was always dissolved. 



3rd. A platina arc was used for connexion instead of gold : the 

 effect was the same. 



4th. The outside of the pipe was coated with gold leaf, leaving 

 scarcely any part exposed : a strip was placed in the muriatic acid 

 as before, and when contact was made with the nitric acid this strip 

 was destroyed, while the coating of gold directly across the line of 

 junction was unhurt. 



5th. The nitric acid was stained with a little tournesol : when 

 contact was made, I could not see that the muriatic acid acquired 

 any of the colour. 



6th. Nitrate of copper was used instead of nitric acid ; the effect 

 was the same, but took place more slowly, and I could detect no 

 precipitation on the negative metal. 



7th. I now made gold leaf in muriatic acid the electrodes of a 

 single pair of voltaic metals ; the acid was decomposed and the posi- 

 tive electrode was dissolved. 



From all this I think we may pronounce the action to be as fol- 

 lows : as soon as the electric current is established, both the acids 

 are decomposed, the hydrogen of the muriatic unites with the oxygen 

 of the nitric, and the chlorine attacks the gold. 



In all these cases the currents were examined with a galvanome- 

 ter, and in all, the gold which was dissolved represented the zinc of 

 an ordinary voltaic combination : the greatest deflection was obtained 

 with platina, gold, and the two acids. It now occurred to me, that 

 as gold, platina, and two acids gave so powerful an electric cur- 

 rent, a fortiori, the same arrangement, with the substitution of zinc 

 for gold, must form a combination more energetic than any yet 

 known. I delayed not to submit this to experiment, and was grati- 

 fied with the most complete success. A single pair, composed of a strij) 

 of amalgamated zinc an inch long and a quarter of an inch wide, a 

 cyhnder of platina three quarters of an inch high, with a tobacco-pipe 

 bowl and an egg cup, readily decomposed water acidulated with sul- 

 phuric acid. In this battery the action is constant, and there is no 

 ]jrccipitation on either metal : it offers the great advantage of being 

 able to utilize the action of concentrated nitric acid. I tried the 

 same arrangement, substituting for the muriatic acid caustic potass, 

 which was suggested to me by a well-known experiment of M. Bec- 

 querel : the action was equally powerful, and I should prefer this 

 arrangement, as there is no necessity for amalgamating the zinc, but 

 for a fatal objection — the nitrate of potass, crystallizing in the pores 

 of the earthenware, splits it to pieces ; excejjt, therefore, a new de- 

 scription of diaphragm l)c discovered which will bear the action of 

 l)owerful acids, this combinati(m must be abandoned. 



I diluted the muriatic acid with twice its volume of water and the 

 efi'ect was not perceptibly inferior. I then tried sulphuric with four 

 or five times its volume of water; the intensity was a little diminished, 

 but so little that I should prefer this combination to any other, as 



