360 



Dr. G. Gore on the Peltier Effect 



composed of thirty-six pairs of bismuth and antimony, at a 

 uniform temperature of 8° Centigrade. The current was then 

 stopped, and the terminals of the pile at once connected with 

 an astatic galvanometer of 100 ohms resistance : the needles 

 gave a swing of 8 degrees. The pile was then heated in a 

 hot- water jacketed chamber to a uniform temperature of 

 65° 0., and the experiment exactly repeated with the current 

 of its original strength : the needles now gave a swing of 17 

 degrees. These experiments were again exactly repeated, 

 but with the pile at 9° C. and 85° C. : the deflections were 

 8 degrees at 9° C. and 20 at 85° C. 



These results indicate that the difference of temperature 

 produced at and near the two junctions of a bismuth and 

 antimony thermo-couple, by the passage of an electric current 

 through them, is more than twice as great at 85° C. as at 8° 

 C. As the amount of resistance of the galvanometer was 

 large in comparison with that of the pile, the increased strength 

 of current was due to increase of electromotive force. 



In order to examine the amount of Peltier effect produced 

 at the two junctions of the pile separately, a current of *2 

 ampere was passed, during about twenty seconds, from A to B, 

 through a cross composed of two wires ; A D being of iron, 

 '5 millim. diameter, and B of German-silver, '4 millim. 

 diameter, whilst their opposite ends, C, D, were attached to a 

 galvanometer, of about 2*0 ohms resistance, by means of 

 slender wires of copper. 



With the entire cross and the adjoining 

 portions of its conducting wires at 10° 0., 

 on passing the current from iron through 

 the junction to German-silver, a deflection 

 of 3 degrees was produced, showing that 

 the junction was heated ; and on passing it 

 from German-silver to iron, the deflection 

 was 2 degrees in the same direction, show- 

 ing that the junction was again heated, but 

 in a less degree. These results were ob- 

 tained several times. On repeating these 

 experiments carefully in a similar manner, 

 but with the cross and its attachments at 

 90° C, the current from iron through the 

 junction to German-silver produced a de- 

 flection of 4 degrees, indicating heat at the 

 junction ; and on passing it from German-silver to iron, the 

 deflection was 2 degrees in the same direction, the junction 

 being again heated. 



These results show — 1st, that with a thermo-couple com- 



