96 PROCEEDINGS OP THE AMERICAN ACADEMY. 



On referring to equation (4), 



E = KT -V h, 

 it is obvious that we have here data for calcuhiting h ; for 

 dE 0.07350 — 0.06836 



dT 24.45 



= 0.0002102. 



Upon this basis, h = 0.01096. But according to our original definition 



h = — , or Q = hneQ. In this case « = 2, and Bq = 23040, expressed 



in such units that if E is in volts, CqE will be in gram calories. Hence 

 we have 



Q = +505 small calories. 



This result represents the small quantity of heat given off when one 

 gram atom (or 112.3 grams) of cadmium is dissolved in 11,100 grams of 

 mercury. The constancy of the quotient in the last column of Table I. 

 shows that further dilution does not increase this heat evolution. 



Class 4. 



A further application of equation (4) is presented in Tables V. and 

 VI., which give the electromotive forces of cells whose electrodes were of 

 zinc and one per cent zinc amalgam. The cells were kept at each tem- 

 perature for ten minutes after constancy was reached. 



Between the observations (4) and (5) in Table V. the thermostat 

 was raised to higher temperatures, but above 37° hydrogen bubbles weie 

 evolved at the solid electrodes and the electromotive force became incon- 

 stant. The thermostat was then cooled to 34.5° and the electrodes were 

 stirred and shaken to drive off the accumulated hydrogen. The readings 

 were then resumed. 



In Table VI. between observations (7) and (8) forty-eight hours inter- 

 vened ; so that the later results are not so trustworthy as the earlier 

 ones. These observations are not used in the calculation, but are given 

 merely in order to show that even a long immersion in the electrolyte 

 does not seem to affect very greatly the condition of the spongy zinc. 



The equation, based upon the starred observations in Table V., is as 



follows : — 



E = 0.0002000 T — 0.04895. 



Everywhere between 0° and 36° the values found agree almost exactly 

 with the values calculated from this formula. 



Here, as before, Q = hneQ ; yi = 2 ; e^ — 23040 ; but in this case 



