Intelligence and Miscellaneous Articles. 299 



The experiment is more striking when two voltameters, arranged 

 as in the first and second case, are placed in the same circuit. In 

 one case there were — 



H . . 929 1204 



20 . .1158 544 



? . . 1-60 4-42 



If the two plates be put into one voltameter and the two wires 

 into the other, without any change in the other arrangements, 

 similar results will be obtained ; the two plates produce but little 

 gas, whilst the two wires furnish a large quantity. A voltameter 

 may be formed with a permanent WoUaston wire, and with a plate of 

 platinum or of some other metal which maybe changed at pleasure ; 

 each plate will disengage (the intensity of the current being the 

 same) very variable quantities of gas, whilst the wire produces a constant 

 action; there is consequently complete independence between the 

 two electrodes. These inequalities may be increased or diminished by 

 very diflferent circumstances ; they become very remarkable in employ- 

 ing the platinum plates of a Grove's battery. The author thus formed 

 two dissymmetrical voltameters, which only produced a disengage- 

 ment of gas at the wires, but none from the plates ; the first furnished 

 nothing but hydrogen, the second only oxygen ; by putting the two 

 plates in the first vessel and the two wires in the second, and passing 

 the current through them, the former allowed it to pass without de- 

 composition, whilst the second produced a great disengagement of 

 gas. This, therefore, has nothing to do with conductibility, but 

 depends on a property peculiar to each electrode. 



As one only of the elements of water is obtained by a dis- 

 symmetrical voltameter, it must be admitted that the one which is 

 not disengaged must combine with the liquid, or become condensed 

 on the plates. These two effects take place simultaneously. 



To show that oxygenated water is produced when hydrogen alone 

 is evolved, all that is necessary is to carry on the decomposition in a 

 cold platinum crucible communicating with the positive pole, immer- 

 sing the negative wire in the fluid which it contains. The author 

 has found that the hydrogenated liquid produced by the evolution of 

 oxygen from water possesses new properties. 



The decomposition of water never takes place without an altera- 

 tion of the electrodes, which is slow, but continuous. The positive 

 electrode becomes yellow, and passes to orange ; the negative 

 acquires a violet colour. These tints gradually increase and blacken, 

 so that it is evident that something is deposited upon the platinum. 

 These deposits disappear in the air, especially when the electrodes 

 are heated. The negative plate becomes clean in nitric acid, and 

 absorbs gaseous oxygen ; the ])ositive plate is cleaned by deoxidizing 

 liquids, and absorbs hydrogen. Lastly, if the two electrodes be im- 

 meraed in acidulated water and united by a galvanometer, they give 

 rise to a current of reaction which lasts several days. These pro- 

 perties acquired by the plates deserve particular attention, and the 

 author thinks they are to be attriljuted to condensation of the two 

 gases on their surfaces. This oj)inion is confirmed by the fact, that 



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