302 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



-2.73° C 



-200° C , 



-100°C 



O'C 



U =: heat of reaction. A = electrical energy. 



Ordinates represent energy, abcissae temperature (Centigrade). 



}Mg-Cu 



}Zu Cu 



Fe-Cu> 

 Ki-Cu 



>■ Zn-Fe 

 J 



] M-Fe^ 



