Electromotive Force of different Forms of the Clark Cell. 131 



§ 15. Results of Observations. 

 Table I. — Temperature-variation of B.O.T. Crystal Cells. 



Tempera- 

 ture C. 

 corrected to 

 nitrogen- 

 scale. 



Difference in millivolts 



Difference from 





from value at 15° C. 



lineality. 



Difference 

 from 











formula 



Observed 



Formula 



Observed 



Calculated 



(P)> 



(0). 



(L). 



(O)-(L). 



formula (p). 



u uu 



+ 16 -62 



+ 18 -00 



-1 -38 



-1 -40 





5-17 



+ 11-15 



+ 11-80 



-0-65 



-0-60 



-0-05 



9-89 



+ 5-92 



+ 6-13 



-0-21 



-Oltf 



-0-05 



20 -43 



- 6-70 



- 6-52 



-0-18 



-0-18 



-o-oo 



24 75 



-12-25 



-11 -70 



-0-55 



-0-59 



+ 0-04 



29-90 



-19-42 



-17-88 



-1 -54 



-1-38 



-0-16 



29-86 



-19-32 



-17*83 



-1-49 



-1-37 



-0-12 



40-60 



-35-81 



-30 72 



-5-09 



-4-07 



-1-02 



Fig. 2. 



o-o 



05 



°D-A5 







y 



* 





_ s. 



\ 

 \\ 

 \\ 



v 







# 



* i/ 



^ — 





of D/'ffe, 





\\ 





/ * 



1 

 1 



W * 



'0/J7 L/'fJt 





77L//d. (L) 



Wc ' 



\\ 



\\ 

 \ \ 

 \ \ 



\ \ 



4 





t 



1 















The results of these experiments on the temperature- variation of 

 the E.M.F. of B.O.T. crystal cells are given in the above table, and 

 are plotted in the accompanying curve (fig. 2). The curve is drawn 

 to show not the whole temperature-variation of the E.M.F. , but the 

 defect of the change from lineality. 



The observed E.M.F. in volts at a temperature t° C. is less at all 

 points than that calculated by the simple linear formula, 



E* = E 15 -0-001,200 (f-15) ... (L). 



The difference from this linear formula is approximately repre- 

 sented by the addition of a parabolic term, 



-0-0000062 (£-15) 2 (P). 



VOL. LX1I. L 



