370 



[Apr. 



A and B by a wire, C, of the same material, fixed on a handle, D, 

 position of which is read on a scale by a pointer, E. - 



A switchboard was used which allowed a current to be sent 

 either direction through the liquid in the calorimeter, or through 

 coil, 7, or through both at once. 



Two methods were employed with this apparatus for measi 

 the Peltier effect at . The first is as follows. 



After all has attained a uniform temperature, the resistance of 

 is measured. A current was then passed through 7 for tl 

 minutes, the liquid being well stirred, and the current being 

 sured. The resistance of /3 is again measured. 



The whole is allowed to stand for a few minutes till the temj 

 ture is steady, and then a current is passed through the liquid by tl 

 plate a, for three minutes, and the resistance of ft is again measni 

 After a rest the current is reversed, and allowed to pass again throi 

 the liquid, and the resistance is again measured. 



When the current is passing through the liquid the heating effe 

 is due to two causes ; one of these is unknown, and is independent 

 the direction of the current. Let C be the current, and let AiP 

 this unknown heat. The rest is due to the Peltier effect, and 

 may put it equal to He. 



