Mr. R. Aclie on some Thermo -electrical Experiments. 185 



current ; and those of the second, fourth, and other even orders, 

 have among themselves one and the same direction. 



With regard to the direction of the currents of even orders as 

 compared with that of the primary current, the author arrives 

 at the probable conclusion, that they also have the same direc- 

 tion as the primary^ but as this portion of the subject remains 

 hypothetical, we will content ourselves with the mere indication 

 of the author's opinion. 



Queenwood College, 

 November 1851. 



XXVIII. On some Thernw-electrical Experiments. 

 By Richard Adie, Esq. 



To the Editors of the Philosophical Magazine and Journal. 

 Gentlemen, Liverpool, Feb. 10, 1852. 



I SHOULD be glad to be allowed to avail myself of the me- 

 dium of your Journal to give a brief notice of some therm o- 

 electrical experiments which I made in the years 1842 and 1843*, 

 and which I believe may be of service in elucidating some of the 

 results noted in your February Number in Dr. Tyndall's inter- 

 esting review of Professor Magnus's researches on this subject. 



Where thermo-elcctrical couples are formed of feebly thermo- 

 electric agents, such as bars of the same metal in different states 

 of density, particularly of the softer malleable metals, the elec- 

 trical force developed is so weak, that slight changes in the mode 

 of manipulation, or small differences in the elements employed, 

 which are cither unknown to the operator or are generated 

 during his experiment, will produce contradictory results. On 

 which account it appears to me to be better to leave that class of 

 agents and first study the production of thermo-electricity by 

 metals, where the force is so decided, that, in the hands of dif- 

 ferent experimenters, uniform actions can be obtained. 



Steel is a substance possessed of the advantage of being readily 

 changed in density in opposite directions by two modes of hard- 

 ening; and as these different methods are accompanied by a 

 thermo-elcctrical current governed in its direction by the kind 

 of hardening employed, the experiments with steel appear to me 

 to show that the molecular arrangement of the particles of a 

 body exercises a constant influence over the thcrmo-electrical cur- 

 rents generated by the unequal heating of it. When a couple is 

 made by joining to a bar of soft steel a similar bar hardened by 

 hammering, on heating the junction of the steel in the two dif- 

 ferent states an electrical current passes from the soft to the hard. 



* See Edinburgh Philosophical Journal, Nos. 70 and 71 • 



