[ 394 ] 

 LIV. Intelligence and Miscellaneous Articles. 



THEORETICAL AND EXPERIMENTAL RESEARCHES ON THERMO- 

 ELECTRICAL CURRENTS. BY M. E. P. LE ROUX. 



THE investigation I have to submit to the judgment of the Aca- 

 demy is divided into nine parts. 



1 . In the first I investigate the conditions of a celebrated experi- 

 ment by Becquerel relative to the production of a thermoelectric cur- 

 rent in a wire twisted in one place. I then show that the condition 

 necessary for the production of the current is the contact of two 

 parts of the wire whose temperatures are different — an opinion which 

 indeed had been already expressed by M. Gaugain. The conclusion, 

 then, to be drawn from the point of view of the possible cause of the 

 disengagement of electricity by heat is, that this cause would not 

 be in the inequality in quantity of the flux of heat transmitted on 

 both sides the heated point. 



2. The second paragraph is devoted to the discussion of the ther- 

 moelectric effects produced on the contact of two masses of the same 

 nature and different temperatures. I point out a cause, not yet 

 remarked, which evidently influences the disengagement of electri- 

 city observed in this case. It is based on the fact, shown succes- 

 sively by M. Babinet and by Mr. W. Thomson, and which I inves- 

 tigate in this memoir, that two fragments of the same metal, one 

 in the natural condition and the other stretched, present thermoelec- 

 trical effects when the temperature of their point of contact is raised. 



3. In the third paragraph I give the results of experiments which 

 I have made on the thermoelectrical relations existing between two 

 wires of different metals, one stretched and the other in the natural 

 state. I examined eight metals, Mr. W. Thomson three. My re- 

 sults are in the opposite direction to his for two of the metals — iron 

 and platinum. 



4. In the fourth paragraph I analyze the various theories pro- 

 posed to account for the effect of heat on the production of thermo- 

 electrical currents ; I call to remembrance the important discovery 

 made by Mr.W. Thomson, of the fact that when electricity traverses 

 a conductor going from a hot to a cold part, it can, according to the 

 nature of the conductor, disengage or absorb heat, and vice versd. 



5. The fifth paragraph commences by the establishment of a para- 

 graph formulated, I believe, for the first time '.—When in a circuit ab- 

 sorptions or disengagements of heat are produced proportional to the 

 simple potver of the intensity of the current, these effects correspond 



proportionally to electromotive forces promoted or overcome. 



This proposition opens a new path for discovering the seat of elec- 

 tromotive forces and valuing their absolute intensity, while mea- 

 surements of the intensity of currents only give us the algebraic 

 sums of the various forces which may exist in a circuit. As regards 

 thermoelectric currents, it must be concluded that the effects disco- 

 vered by Peltier and by Mr. W. Thomson point out the existence of 

 electromotive forces and enable. them to be measured. 



What is the part of each of these kinds of electromotive forces 

 (which I shall speak of as Pelterian and Thomsoniari) ? This is exa- 

 mined in the next paragraph. 



6. In this sixth paragraph I first estimate the calorific effects of a 



