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X. On the Temperatures of Conductors of Electrical Currents. 

 By Richard Adie, Esq., Liverpool^. 



THE experiments which have led to the discussion in the 

 pages of this Journal between Dr. Tyndall and myself on 

 the subject of the reduction of temperatures by electricity, took 

 their origin some nine years ago in an examination I made of 

 the thermo-electric cross. I remember I found it a most diffi- 

 cult experiment to explain ; and as Dr. Tyndall in his last com- 

 munication in your December Number speaks of the mysterious 

 action of the outlying arms of this cross, I will briefly detail the 

 examination I then made ; and by doing so I think I shall show 

 that I have not omitted to vary the currents employed, but, on 

 the contrary, have gone through the widest possible range of 

 currents in order to estabhsh the general law of the unequal 

 heating effect of an electrical current. In the thermo-electric 

 cross, this property of electricity heating bars unequally gives 

 rise to an apparent refrigeration at its centre for electricity of 

 every degree of tension ; while M. Peltier, in his announcement 

 of the production of cold by electricity, says that a feeble elec- 

 trical current must be used to show it. 

 The annexed diagram represents the 

 thermo-electric cross, where BD is a 

 bar of antimony, CE a similar bar of 

 bismuth, fastened in good metallic 

 contact at their centres A. HB and 

 CI are wires for connecting with a 

 galvanic battery ; EF and DG are si- 

 milar wires for connecting with a gal- 

 vanometer. When a current is circu- 

 lated through the joint A in the di- 

 rection BAG, a galvanometer in con- 

 nexion with the terminal wires F and G 

 is deflected as if the joint Awas^eated. 

 Again, when the current is circulated in the opposite direction 

 CAB, the action on the galvanometer is the same as if the 

 joint A was cooled. This result is constant for electrical 

 currents varied in tension from feeble thermal sources up to 

 powerful currents used in blasting gunpowder. The appli- 

 cation of a thermometer to the joint A soon shows that it 

 is heated slightly with the feeble currents and more distinctly 

 with those of higher tension. According to M. Peltier, it should 

 be heated by the currents of high tension, but refrigerated by 

 those of low tension. The explanation of this apparently intri- 

 cate experiment is, that the galvanometer is not then measuring 

 * Communicated by the Author. 



