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XXXIII. On the unequal Heating Effect of a Galvanic Cwn-ent 

 ivhile entering and emerging from a Conductor. By Richard 

 Adie, Esq. 



To the Editors of the Philosophical Magazine and Journal. 

 Gentlemen, Liverpool, July 5, 1852. 



IN your Supplementary Number for July, p. 529, I observe 

 a paper by Prof. W. Thomson, wherein he alludes to M. 

 Peltiei-'s experiment on the supposed absorption of heat by a 

 bismuth and antimony joint while conducting a feeble galvanic 

 current passing (on the supposition of there being one current 

 only) from the bismuth to the antimony. In the year 1843, I 

 made some experiments connected with this subject, and as I 

 came to conclusions which gave a different explanation to M. 

 Peltier's researches, I should be glad to avail myself of the me- 

 dium of your Joui-nal briefly to notice them. 



Among the metals bismuth stands as the most imperfect con- 

 ductor of electricity; and as the heat developed by an electrical 

 current passing along a bar is in proportion to the resistance to 

 conduction, it follows that, in compound metallic bars of uniform 

 sectional area throughout, the bismuth portion is more heated 

 than the other parts. In a compound bar composed of antimony, 

 bismuth and antimony, again, when a feeble galvanic current is 

 made to pass through this arrangement, the conditions required 

 for observing M. Peltier's experiment are supplied; for at the 

 one end of the bismuth bar the current through the joint is 

 from antimony to bismuth, while at the other end of the bis- 

 muth bar the passage through the joint is from bismuth to an- 

 timony. To ascertain the temperatures at these joints, two 

 delicate thermometers are attached and enveloped with a little 

 dry cotton wool. A galvanic current made to pass through this 

 arrangement elevates the thermometer where the electricity enters 

 the bismuth more than the one where it quits the bismuth ; the 

 difference between these two thermometers varying with the 

 changes in the battery from which the electrical cm-rent is de- 

 rived. Now, according to Peltier's views, the thermometer at 

 the joint where the current passes from the bismuth to the 

 antimony, should, dming the conduction of a feeble current, 

 stand lower than the temperature of the atmosphere ; to ascer- 

 tain this point I have frequently repeated the experiments with- 

 out being able to note any absorption of heat. With me the 

 thermometer stands a little above the temperatui-e of the atmo- 

 sphere; and from a brief notice I have seen of M. Becquerel's 

 investigation of this question, I believe that he has likewise failed 

 to note any absorption of heat. The two joints of the bismuth 



