at different Temperatures. 361 



posed of iron and German-silver, a current of uniform strength, 

 passed from iron to German-silver, evolved more heat than 

 when passed in the opposite direction, whether the pile was at 

 10° 0. or 90° C. 2nd, that when the current was passed from 

 iron to German-silver, it evolved more heat at and near the 

 junction when the couple was at 90° 0. than when it was at 

 10° C. And 3rd, that when it was passed from German-silver 

 to iron, the amounts of heat evolved were about the same 

 when the couple was at 90° as when it was at 10° C. 



With the same strength of current, and a cross formed of 

 bismuth and antimony, with the cross and its connections at 

 12° C, on passing the current from the bismuth through the 

 junction to the antimony, a deflection of 8 degrees was pro- 

 duced, showing that the junction was cooled ; and on passing 

 it in the opposite direction, the deflection was 8 degrees in 

 the opposite direction, showing a heating effect. With the 

 cross, &c, at 93° C, passing the current from the bismuth 

 through the junction to the antimony produced a deflection 

 of 10 degrees and a cooling effect ; and passing it in an 

 opposite direction produced a deflection of 10 degrees and a 

 heating effect. 



From these results it appears that the Peltier effect, both 

 of heating and cooling, with a thermo-couple of bismuth and 

 antimony, was considerably larger at 93° than at 12° C. 

 Also that the amounts of heating and cooling effect were 

 about equal, whether the couple was at 12° or 93° 0. 



Similar experiments were made with a cross formed of 

 bismuth and silver, and with one composed of antimony and 

 silver, the silver wire being *5 millim. diameter, with the same 

 strength of current as before. The results were as follows 

 (the direction of current given in each case is that through the 

 junction) :— Bigmuth and gUver ftfc 12 o a 



Direction of Current. Deflection. Thermal Effect. 



From Bi to Ag 2'0 Junction cooled. 



„ AgtoBi 2-0 to 2-5 „ heated. 



Bismuth and Silver at 92° C. 



From Bi to Ag 3*0 Junction cooled. 



„ AgtoBi 3*0 „ heated. 



Antimony and Silver at 12° C. 



From SbtoAg 1*5 Junction heated. 



„ AgtoSb 1-5 „ cooled. 



Antimony and Silver at 95° C. 



From SbtoAg 1>5 Junction heated. 



„ AgtoSb 1-5 ,, cooled. 



