Slate of Tension between the Zinc and Water, .^ 1 75 



case tlie forces determined in opposite directions, with respect 

 to the zinc and the electrolyte, are found exactly competent 

 to neutralize each other, then a series of decompositions and 

 recompositions takes place amongst the particles of oxygen 

 and hydrogen constituting the water, between the place of 

 relief and the place where the zinc is active; these interven- 

 ing particles being evidently in close dependence upon and 

 relation to each other. The zinc forms a direct compound 

 with those particles of oxygen which were, immediately be- 

 fore, in divided relation to both it and the hydrogen : the 

 oxide is removed by the acid, and a fresh surface of contact 

 between the zinc and water is presented, to renew and re- 

 peat the action. 



950. Practically, the state of tension is best relieved by 

 dipping a metal which has less attraction for oxygen than the 

 zinc, into the dilute acid, and making it also touch the zinc. 

 The force of chemical affinity, which has been influenced or 

 polarized in the particles of the water by the dominant attrac- 

 tion of the zinc for the oxygen, is then transferred, in a most 

 extraordinary manner, through the two metals, so as to re- 

 enter upon the circuit in the electrolytic conductor, which can- 

 not convey or transfer it without decomposition as the metals 

 can ; or rather, probably, it is exactly balanced and neutralized 

 by the force which at the same moment completes the combi- 

 nation of the zinc with the oxygen of the water. The forces, 

 in fact, of the two particles which are acting towards each 

 other, and which are therefore in opposite directions, are the 

 origin of the two opposite forces, or directions of force, in the 

 current. They are of necessity equivalent to each other. Being 

 transferred forward in contrary directions, they produce what 

 is called the voltaic current : and it seems to me impossible to 

 resist the idea that it must be preceded by a state of tension 

 in the fluid, and between the fluid and the zinc; xh^first con- 

 sequence of the affinity of the zinc lor the oxygen of the water. 



951. I have sought carefully for indications of a state of 

 tension in the electrolytic conductor ; and conceiving that it 

 might produce something like structure, either before or du- 

 ring its discharge, I endeavoured to make this evident by po- 

 larized light. A glass cell, seven inches long, one inch and a 

 half wide, and six inches deep, had two sets of platina elec- 

 trodes adapted to it, one set for the ends, and the other for the 

 sides. Those for the sides were seven inches long by three 

 inches high, and when in the cell were separated by a little 

 frame of wood covered with calico ; so that when made active 

 by connexion with a battery upon any solution in the cell. 



