1052 
(K)« represents the electric energy of the a-cell at 7°; (Ha the 
quantity of heat which is generated if at 7° one gram atom of 
a-Cadmium is dissolved in an unlimited quantity of cadmium amal- 
gam (8 percent by weight). 
The signification of (/.), and (£,), is quite analogous. 
6. From our equations we get: 
dE, dE, 
(£.), ey (B) = NE | 29, irr (Ee) nn (Gz) - EM k (1) 
The expression on the left represents the heat of transformation 
which accompanies the change of J gram atom y-cadmium into 
a-cadmium, i. e. the value to be determined. 
Therefore we have only to measure the E.M.F. as well as the 
temperature coefficients of the a- and y-cell at 7°. 
7. As we pointed out some time ago the cells which have been studied 
by Hererr *) are our y-cells. From his determinations between 0° 
and 40° ©. it follows that 
(H,)® = 0.05047 —0.0002437 (t —25) Vole. . . . (2) 
8. We constructed our a-cells starting from y-cells, in which the 
y-cadmium was transformed into «-cadmium. 
The way in which these y-cells were prepared and in which their 
E. M. F. was determined has been described in full in our third 
paper on the allotropy of cadmium. *) As standard cells we used 
two Weston-cells and two CLARK-eells which were standing in a 
thermostat at 25.°O. The E. M. F. of the Wesror-cell was assumed 
to be 1.0181 Volt at 25°.0. 
E. M. F. Crark 
E. M. F. Weston 
Oct. 31. 1914 1.3948 
Dec. 17. 1914 1.3947 . 
Jan. 19. 1915 1.3947 
We prepared 11 ytells. At 25°.0 their E.M. F. was 0.0504 Volt. 
After standing for a fortnight at 25°.0 the y-cadmium was trans- 
formed into the /°-modification as was shown by the fact that the 
E. M. F. had decreased to 0.048 Volt at 25°.0. In order to trans- 
form the g-modification into a-cadmium we put the cells for a 
fortnight into a thermostat which was kept at 47°.5 C. We now 
The ratio ( ) was found to be: 
25°.0 
1) Trans. Americ. electrochem. Soc. 15, 435 (1909). Hurerr used a 10 percent 
amalgam (by weight). This is a two-phase system between 0° and 40°. 
2) These Proc. Vol. XVII. p. 122. 
