378 Intelligence and Miscellaneous Articles. 



(4) If, in the experiment I have just spoken of, six Bunsen ele- 

 ments be substituted for the Daniell battery, the decomposition, as 

 might have been expected, takes place with much more intensity- 

 After 18 hours the quantity of oxide of silver, in part reduced, 

 found at the bottom of the tube is relatively considerable. 



(5) G-old employed as the positive electrode is not oxidized in the 

 presence of distilled water, even by the action of the current of 

 eight Bunsen elements. 



Is silver, then, the only metal which possesses the property of 

 decomposing distilled water under the action of a galvanic current ? 

 No, fortunately ; for it might be objected to me that, if water is 

 decomposed when silver serves for the positive electrode, it may be 

 due to this — that the oxide of silver, being soluble in water*, 

 always suffices to render the water sufficiently conductive to be 

 electrolyzed. This objection, however, would not be quite relevant ; 

 for it would not account for the current passing at the commence- 

 ment of the experiment, since at that moment the water contains 

 no foreign substance, and it is only after some time that the silver 

 begins to dissolve. Therefore it is not the oxidation of the silver 

 that permits the current to pass ; but it is the current that, by 

 decomposing the water, oxidizes the silver. It is true that, once 

 the water contains a little oxide of silver, its conductivity is in- 

 creased, and consequently electrolysis can take place with more 

 facility ; but, I repeat, the oxidation of the silver is not the deter- 

 mining cause of the decomposition of the water, but only the effect 

 of that decomposition. Be that as it may, here is an experiment 

 which will show positively that the solubility of the silver oxide 

 plays only a secondary part in the electrolysis of distilled water : — 



(6) The oxides and the hydrates of copper are completely inso- 

 luble in distilled water; and hence they cannot in any way augment 

 the conductivity of the water. Now I have found that copper 

 possesses, like silver, the property of decomposing distilled water 

 when it is connected with the positive pole of a battery. The ex- 

 periment is made as before ; that is to say, a platinum wire and a 

 Copper wire are immersed in the two branches of a U-tube filled 

 with distilled water, the former joined to the negative, and the 

 latter to the positive pole of a battery composed of three Daniell 

 elements. The distance separating the two electrodes is about 

 4 centimetres. At the end of 18 hours, upon a length of about 

 2 centim. at the lower part a coat of reduced copper is found adhe- 

 ring to the sides of the tube. A portion of the copper is deposited 

 on the platinum wire. The decomposition of the water in this case 

 can be explained only on the hypothesis that the copper employed 

 as the positive electrode tends to diminish the resistance of the 

 water, and consequently to render it more apt to be electrolyzed. 

 It is the same with silver employed as positive electrode. — Comptes 

 Rendus de TAcademie des Sciences, April 5, 1882, pp. 948-951. 



* Oxide of silver dissolves in 3000 times its weight of water. 



