Chemical Affinity in terms of Electromotive Force. 335 



Water jacket 

 warmer than 

 room. Calori- 

 meter colder 



than jacket 

 and warmer 



than room. 



Water jacket 

 colder than 

 room. Calo- 

 rimeter colder 

 than jacket and 

 colder than 

 room. 



Water jacket 

 colder than 

 room. Calori- 

 meter slightly 

 warmer than 

 jacket and 

 colder than 

 room. 



Water jacket 

 colder than 

 room. Calori- 

 meter warmer 

 than jacket 

 and slightly 

 colder than 

 room. 



Obs. 



-4-8 

 -4-0 

 -36 

 -3-2 

 -2-4 

 -1-5 

 -09 

 -01 

 4-0-9 

 -fl-2 

 +1-5 

 4-1-8 



Calc. 



Obs. 



Calc. 



Obs. 



Calc. 



Obs. 



Calc. 



-4-9 

 -4-1 

 -3-6 

 -27 

 -2-0 

 -1-3 

 -0-7 





 +0-7 

 +1-3 

 4-1-8 

 4-2-1 



-8-0 

 -7-4 

 -7-0 

 -51 

 -4-8 

 -4-3 

 -38 

 -3-6 



-8-2 

 -73 

 -6-7 

 -5-4 

 -4-8 

 -4-3 

 -3-9 

 -3-5 



4-0-2 

 -0-2 

 -0-7 

 -1-0 

 -1-5 

 -1-4 

 -1-0 



4-0.1 

 -0-2 

 -0-6 

 -1-0 

 -1-2 

 -1-2 



+2-3 

 + 1-9 

 4-1-2 

 4-1-0 

 +0-8 

 +0-3 

 4-0-2 



+2-3 

 4-1-9 

 4-14 

 4-1-3 

 +0-8 

 +0-3 

 



42. It is evident from these numbers that the difference 

 between the observed and calculated rates of alteration per 

 hour rarely exceeds 0*2 millimetre, and averages much less ; 

 so that the difference between the results deduced by the for- 

 mula and those attained by direct observation is practically 

 negligible for all experiments lasting for only half an hour or 

 less. In order, however, to diminish any error in the radia- 

 tion-correction caused by the use of the formula, a threefold 

 determination was made, as follows, the average of the three 

 observations being taken. First, the correction was esti- 

 mated from the observed average values of M and N through- 

 out the experiment. Secondly, the rate of alteration of tem- 

 perature of the calorimeter (rising) before the experiment was 

 commenced was determined by observations made for 30-60 

 minutes before commencing; and, similarly, the rate of altera- 

 tion (falling) was determined by observations made for 30-60 

 minutes after concluding, and the mean of the two rates 

 taken. Thirdly, the rate of alteration at the commencement 

 of the experiment was calculated from the values of M and N 

 then observed; and similarly the rate of alteration at the close 

 was calculated from the then values of M and N, and the mean 

 taken as before. The three values rarely differed from their 

 mean by so much as 0*1 millimetre per hour. Thus the fol- 

 lowing values were obtained in an experiment lasting eighteen 



