the Galvanic Battery. • 53 



molecules of hydrochloric acid arranged in polar order from zinc 

 to copper. If we remove from our diagram the chlorine from 

 one end and the hydrogen from the other, we have a chain of mole- 

 cules in the order in which they are kept after the first action, 

 an order which we may call antipolar. If matters remained 

 in this order, there could be no further combination of zinc 

 with chlorine, no further liberation of hydrogen on the cop- 

 per. We see that there can be no continuous current without 

 a motion of the atoms : the atoms of chlorine must come in 

 contact with the zinc to combine with it, and the atoms of 

 hydrogen in contact with the copper to escape from it, and the 

 original polar arrangement must re-establish itself throughout 

 the whole liquid from the zinc to the copper before the next 

 decomposition ensues. It would be unnecessary to discuss at 

 present the particular manner in which this atomic motion takes 

 place in the conducting liquid; but there is no doubt of the fact 

 that each atom of chlorine has to take the hydrogen from another 

 atom of chlorine after each decomposition, and then to get over 

 so as to touch the positive plate, while the hydrogen gets next 

 to the negative plate. These atomic motions have been long 

 since shown to take place in the conducting liquid." 



In the Philosophical Magazine, vol. xxv. (1844), there is a 

 paper by the late Professor Daniell and Dr. Miller, in which is 

 announced the fact that a mutual transfer of the elements of a 

 decomposing salt by an electric current does not take place: 

 and my own experiments, an account of some of which was read 

 before the Chemical Society several years ago, made with a 

 variety of salts in solution, both on a large and small scale, also 

 show that the acid element of a salt is alone transferred by an 

 electric current. 



Suppose a vessel divided by a porous diaphragm have dissolved 

 in each division an equal quantity of a salt (say sulphate of cop- 

 per), and into each of the divisions is placed a plate of metal 

 (say copper) attached to the poles of a battery, which com- 

 pletes the circuit. Now by Professor Williamson's assumed 

 theory, there would be a mutual transfer of the acid and copper 

 between the two divisions, so that at any time, if the operation 

 or current of electricity was stopped, the solutions in the two 

 divisions w ould be the same as when the experiment began ; but 

 the facts of the case are not so. The copper in solution in the 

 division attached to the zinc plate of the battery will be depo- 

 sited as metal on the copper plate in that division, while the acid 

 element will be transferred to the other division ; but the copper 

 in that other division will not come into the division in the oppo- 

 site direction of the acid; so that at the end, the one division 

 will have neither copper nor acid in solution, and the other 



