Intelligence and Miscellaneous Articles. 393 



wivariably exhibit local currents, which return into themselves in the 

 same piece by various windings ; and as those currents always affect 

 the general current in the circle, it was necessary to explain the 

 operation of those local currents in the first place, and to guard against 

 their influence when contemplating the operation of general currents, 

 supposed to arise from other causes than that of crystalline groups of 

 metallic films. 



For this purpose I cast rectangular frames, of the same fashion as 

 those I had before employed, of an alloy of tin and bismuth, in which 

 no local or other current could be detected, to whatever point heat 

 was applied j owing, no doubt, to the crystallization of the bismuth 

 being nearly neutralized by the admixture of tin. 



When one end of a frame was cut open by a fine saw, and one side 

 of the opening warmed in the flame of a spirit-lamp, the whole frame 

 became magnetic whenever the warm and cool sides were brought 

 into contact, as if an electric current set through the saw-cut, from 

 the heated to the cool extremity. I employed no multiplying gal- 

 vanometer j simply sprung the sides of the opening together, and 

 operated as with the whole frames of antimony, bismuth, &c. 



I had placed a good deal of importance in this discovery, until I 

 found that the phenomena were not uniform in all the metals ; for 

 although the current passes through the opening from the heated to 

 the cool extremity in some metals, as in copper, brass, &c, it as 

 constantly flows in the opposite direction in zinc, iron, &c. ; just as 

 I have shown to be the case with brass, and steel partially hardened, 

 and perhaps for the same reason. 



The facts, however, are certainly interesting : in a theoretical point 

 of view, none, perhaps, are more so. 



Suggestions on the Electro- Decomposition of Metallic Solutions. 



In the electro-decomposition of metallic solutions, and perhaps in 

 that of all others, it appears to be an invariable law, that the constituent 

 carried to the negative pole is the better electric conductor. This 

 being an established fact, it is probable that the same law would be 

 observed when more than one metal is held in the solution operated 

 on. The best conductor in such solutions ought to be carried to the 

 negative pole in preference to any of the rest ; or at least in an earlier 

 part of the process. For instance : a solution of copper and zinc in ni- 

 trous'acid. The copper, being a better conductor than the zinc, ought, 

 according to this law, to be revived at the negative pole in the earliest 

 part of the process, and the zinc not until a later period. Upon 

 the same principle, gold ought to be recovered before zinc from a 

 solution holding them both. And for the same reason, any metal 

 suspected to be a compound ought to have its constituents separated 

 by a similar process. The same law, if universal, ought to be ob- 

 served in all metallic solutions whatever. If, therefore, those metals 

 which are apparently the most pure and simple should still happen to 

 be compounds, it is highly probable that, by attending to, and ope- 

 rating upon, this principle, their decomposition would be very much 

 facilitated, if not entirely accomplished. 



Third Series. Vol. 3." No. 17- Nov. 1833. 3 E 



