428 Prof. E. Edlund on the Thermal Phenomena of the 



The outer tube being filled with water, the bar of copper 

 heated to a dark red is placed in the inner tube, the cap ad- 

 justed, and a rock-salt plate ^o °f an inch thick shaped thus 



I w ^3 placed on the^to pof the cap, the blotting-paper 



with its waxed surface downwards brought immediately over 

 but not touching the salt : the heat ascending melts the wax, 

 and a well-defined outline of the rock-salt plate is produced on 



the upper surface of the blotting-paper, thus 



If the experiment be performed without the rock-salt plate, the 

 melted wax first shows itself as a dark spot in the centre of the 

 blotting-paper, and then spreads towards the edges. Different 

 shaped plates were used with similar results. Tn performing 

 the experiment care must be taken that the heated copper 

 stands fairly perpendicular under the centre of the cap. 



LV III. On the Thermal Phenomena of the Galvanic Pile, and 

 Electromotive Forces. By E. Edlund*. 



§i- 



1. lj^ROM the experiments which have been instituted for 

 J- the purpose of studying the thermal phenomena of 

 the galvanic pile and its conductors the conclusion has been 

 drawn, that the heat which arises in consequence of the pas- 

 sage of the current through the entire conduction (including 

 the pile itself) during a certain time is exactly equal in quan- 

 tity to that which is produced in the pile by chemical pro- 

 cesses during the same time, — that is to say, provided that 

 the current performs no external work (for example, induc- 

 tion, chemical decomposition, &c); and among the pro- 

 cesses mentioned, only those must be understood which are 

 primary and in direct connexion with the formation of the 

 current. In the following, to distinguish these two quantities 

 of heat from one another, we will name that which is occasioned 

 by the passage of the current through the conductors the gal- 



* Translated from a separate impression, communicated by the Author 

 from PoggendorfPs Annalen, vol. clix. pp. 420-456. 



