Apparent Conversion of Electricity into Mechanical Force. 235 



111. Of these equations, (7) and (3), from which (7) is derived, 

 involve no hypothesis whatever, but merely express the applica- 

 tion of a great natural law — discovered by Joule for every case of 

 thermal action, whether chemical, electrical, or mechanical — to 

 the electrical circumstances of a solid hnear conductor having 

 in any way the property of experiencing reverse thermal effects 

 from infinitely feeble currents in the two directions through it. 

 Equation (9) expresses the hypothetical application of the second 

 general law discussed above in § 106. The two equations, (7) 

 and (9), express all the information that can be derived from the 

 general dynamical theory of heat, regarding the special thermal 

 and electrical energies brought into action by inequalities of 

 temperature, or by the independent excitation of a current in a 

 solid linear conductor, whether crystalline or not. The con- 

 dition that the circuit is to be linear, being merely one of con- 

 venience in the initial treatment of the subject, may of course be 

 removed by supposing linear conductors to be put together so as 

 to represent the circumstances of a solid conductor of electricity, 

 with any distribution of electric currents whatever through it ; 

 and we may therefore regard these two equations as the funda- 

 mental equations of the mechanical theoiy of thermo-electric 

 currents. To work out the theory for crystalline or non-crystal- 

 line conductors, it is necessary to consider all the conditions 

 which determine the generation or absorption of heat in diffei-ent 

 parts of the circuit, whatever be the properties of the metals of 

 which it is formed. This we may now proceed to do ; first for 

 non-crystalline, and after that for crystalline metals. 

 [To be continued.] 



XXVIII. Some Experiments showing the apparent Conversion of 

 Electricity into Mechanical Force. By W. R. Grove Esq 

 FR.S., i^c. ^'' 



To the Editors of the Philosophical Magazine and Journal. 



Gentlemen, 

 N a communication* made to the members of the Royal Insti- 

 tution, on Friday, January 25th, entitled "Inferences from the 

 Negation of Perpetual Motion," I showed an experiment which, 

 with one or two others now added, may be thought worth re- 

 cording in the Philosophical Magazine. They are hardly, I 

 think, likely to be deduced from our received electrical theories, 

 though possibly not inconsistent with some of them. 



I 



* [An abstract of this communicntion will appear in our Number for 

 April.— Eds.] 



