250 Mr. Smee's New Dejinition of the Voltaic Circuit, 



gently at the top, so that the two fluids do not mix to any 

 great extent, and a copper wire be then placed throughout 

 the whole length of the tube, it will speedily show signs of 

 action. The copper in the acid will rapidly dissolve, whilst 

 copper will be as freely deposited at the lower part of the 

 vessel. Now copper will undergo no action alone, either in 

 muriatic acid or sulphate of copper. This experiment may 

 be varied by the use of different acids or even some salts at 

 the upper part of the vessel, for although muriatic acid shows 

 this experiment most strongly, dilute sulphuric acid or mu- 

 riate of ammonia will produce the same result. 



Silver reduces silver by placing one end of a silver wire in 

 a porous tube containing nitrate of silver, the other in dilute 

 sulphuric acid, though the metal placed in either separately 

 is not affected. 



Lead reduces lead by immersing one end of a piece of lead 

 in a solution of the tris-nitrate of lead, the other in dilute 

 nitric acid. 



Tin reduces tin by placing one portion of a piece of metal 

 in muriate of tin, the other in muriatic acid. 



Gold even reduces gold by immersing one end of a gold 

 wire in the chloride, the other in dilute muriatic acid, the two 

 solutions being separated as in all the former cases by a po- 

 rous diaphragm. 



There is a beautiful experiment detailed by Mr. Grove, 

 which is analogous to those last described, though he attri- 

 buted the results to a different cause*. His experiment is to 

 place two pieces of gold wire in muriatic and nitric acid, sepa- 

 rated by a porous diaphragm, when no action will take place 

 on either, but on being connected, that in muriatic acid will 

 rapidly be dissolved, and the nitric acid will at the same time 

 be decomposed by the hydrogen transferred to the other part 

 of the wire. 



From the various experiments which I have examined, 

 added to the extensive researches of Faraday on the chemical 

 portion of the voltaic pile, the voltaic phaenomena may be de- 

 fined to be certain effects produced by the chemical action of 

 a body on one element of a compound, and manifested be- 

 tween this point of action and the evolution of the second 

 element. The voltaic phaenomena might in other words also 

 be defined to be peculiar properties evinced between the che- 

 mical action of a body on one element of a compound, and 

 the evolution of the second element, the point of abstraction 

 and subsequent combination of the first element being called 

 the positive pole j the point of evolution or removal of the 

 second element of the compound body, the negative pole. 

 [* See Phi!. Mag., Third Series, vol. xiv. p. 388.— Edit.] 



