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XLIV. New Definition of the Voltaic Circuity with Formula? 

 for ascertaining its Power under different circumstances. 

 By Alfred Smee, F.R.S.* 



Theory of the Voltaic Circuit. 



IN conducting my experiments on the reduction of alloys, 

 certain phaenomena and peculiarities were noticed that 

 have so important a bearing on the theory, or rather the 

 rationale of the voltaic current, that it becomes my duty 

 at once to draw up the curtain and expose the conclusions 

 to which they lead, as a knowledge of them will give to the 

 operator great advantages, and enable him, by rightly un- 

 derstanding the force with which he is working, to conduct 

 his various processes to the best possible advantage. 



In these experiments I noticed that in various mixed solu- 

 tions the quantity of voltaic force passing was not at all de- 

 pendent on the nature of the negative element, but upon the 

 ease with which the hydrogen was removed from it. Thus in 

 a solution of sulphate of zinc very slightly acidulated the hy- 

 drogen could not be evolved from smooth copper, but would 

 rather reduce the sulphate of zinc when connected with a 

 small battery. The substitution of smooth platinum in no 

 way added to the power, but the employment of platinized 

 platinum caused an abundant evolution of gas, even to the re- 

 moval of the zinc already reduced on the smooth platinum. 

 Any metal having but little affinity for hydrogen caused a si- 

 milar result; thus, iron caused gas to be evolved and increased 

 the force passing, when smooth platinum would not have the 

 effect, and even zinc itself caused a little gas to be evolved, 

 because the adhesion of the gas to it is slighter than the ad- 

 hesion to smooth platinum. 



In the same way I observed that nitric acid allowed far 

 more electricity to pass than sulphate of copper; and that 

 again, than dilute sulphuric acid, simply from the facility with 

 which hydrogen reduces these substances being greater than 

 the facility of its evolution. I moreover noticed in other 

 cases that the hydrogen would rather be evolved than re- 

 duce a metallic salt, — as sulphate of zinc ; — and in every case 

 that the facility of its removal affected the amount of power 

 passing, quite independently of the nature of the negative 

 plate. 



Now these facts appeared to me a positive proof of there 

 being no such thing as a negative plate contributing to the 



* Reprinted, with additions and corrections by the author, from a pam- 

 phlet extracted, for private circulation, from his "Elements of Electro-me- 

 tallurgy." 



