138 Dr. C. F. Schoenbein on some 



spoken of. According to my opinion, chlorine or bromine bears 

 a similar relation to the hydrogen of water that distilled or amal- 

 gamated zincdoes to the oxygen of (acidulated) water : in either 

 case there is no apparent chemical action, i. e. no decom- 

 position of water previously to a circuit being formed or a 

 path opened for a current. But no sooner has the circuit been 

 completed in our two cases, than both the decomposition 

 of water, and the formation either of muriatic acid or oxide of 

 zinc, begins to take place, and a current makes its appearance. 

 So far the two cases appear entirely similar to each other, but 

 there is some essential difference between them which I will 

 point out. In one case, chlorine is hydrogenized at the ex- 

 pense of the hydrogen of water, in the other zinc is 

 oxidized at the expense of the oxygen of water ; in one case 

 oxygen is set free at the chlorine, in the other hydrogen is 

 evolved at the zinc ; or what comes to the same, in one case 

 hydrogen is transferred from water to chlorine, in the other 

 case oxygen is carried over from water to zinc. Now it is 

 very easy to conceive that chemical actions being so diametric- 

 ally opposite to each other as those in question obviously are, 

 cannot produce the same electro-motive effect, in other terms 

 cannot cause the electrolyzation of water in the same manner. 

 Let usconsider in what way water is electrolyzed in each of 

 the cases under discussion. The particle of oxygen separated 

 from one molecule of water by a particle of chlorine, unites 

 with the hydrogen contained in the molecule of water which 

 is contiguous to the oxygen disengaged, the oxygen of the 

 latter molecule of water combines with the hydrogen of a 

 third one, and so on, until the whole row of contiguous par- 

 ticles of water placed between the electrodes (the ends of the 

 wire connecting the two fluids) have undergone a similar de- 

 composition and recomposition, and oxygen is at last dis- 

 engaged at the positive electrode. The atom of hydrogen 

 eliminated by the action of zinc from the molecule of water 

 which is in immediate contact with that metal associates 

 itself with the oxygen of a third molecule, and so on, until an 

 atom of hydrogen is evolved at the negative electrode. From 

 what I have just now stated it appears that the particles of 

 oxygen contained in the molecules of water approach zinc 

 whilst they recede from chlorine, or that the atoms of hydro- 

 gen move towards chlorine whilst they recede from zinc. If it 

 be admitted that a current passing through an electrolytic body 

 is made up by or is identical with a succession of chemical 

 decompositions and recompositions which the molecules cf 

 the electrolyte undergo, we can easily conceive that what we 

 term the direction of a current is determined by the direc- 



