302 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



-2.73 °C 



-200° C 



-100°C 



0°C 



>Mg-Cu 



yZnCu 



Fe-Cvi> 

 Ni-Cu 



Zn-Fe 



} M-Fe\ 



U = heat of reaction. A = electrical energy. 



Ordinates represent energy, abcissae temperature (Centigrade). 



