210 On the Heating Power of the Galvanic Current. 



a screw form and enclosed in two small glass tubes which werd 

 filled, the one with oxygen and the other with hydrogen; the 

 tubes were immersed in two similar vessels containing equal 

 quantities of water, which served as a calorimeter. When the 

 circuit was established, the wire immersed in the oxygen became 

 white-hot, while that in the hydrogen exhibited no visible red- 

 ness. At the same time the heat yielded by the wires raised the 

 temperature of the suiTOunding water, that in which the hydro- 

 gen tube was immersed being elevated from 60° to 70°, and 

 that which surrounded the oxygen tube, from 60° to 81°. 



In a similar manner Grove compared other gases with hydro- 

 gen, and found the following numbers, which have been reduced 

 by M. Clausius, who takes the quantity of heat yielded in each 

 experiment by the hydrogen as unit : — 



In publishing a translation of the first communication of Grove 

 upon this subject, Poggendorfi" expressed the opinion* that the 

 cooling of a wire heated by galvanic electricity in different gases fol- 

 lows mutatis mutandis the same laws that Dulong and Petit have 

 established in the case of bodies heated in an ordinary manner, and 

 according to which hydrogen possesses the greatest cooling 

 capacity. This manner of explanation is objected to by J. Miiller 

 in his " Report on the latest Progress of Physics,'^ p. 396 ; th6 

 last-mentioned experiment being regarded by him as unmistake- 

 ably opposed to such an explanation. He says : — " This experi- 

 ment proves decidedly that the feebler glowing of the wire ill 

 hydrogen, with an equal strength of current, is not to be referred 

 to the circumstance that the hydrogen abstracts the heat most 

 quickly from its wire, for in this case the water surrounding the 

 hydrogen tube must be most speedily heated. All the circum- 

 stances point to the conclusion, that in the wire surrounded by 

 hydrogen the actual quantity of heat produced is less than in 

 the other wires." Miiller closes his report with the statement, 

 that in his opinion the experiment stands " completely isolated 

 and unaccounted for." 



M. Clausius, however, can find no such difficulty attached to 

 the subject. The different quantities of heat yielded up by the 

 wire in different gases, in connexion with the dependence of the 

 quantity of heat developed by the current upon the resistance of 

 the wire, appear to him to be quite sufficient to explain the phse- 



* Fogg. Ann. vol. Ixxi. p. 197. 



