Chemical Equilibrium of Solids. 



17 



11. A graphic construction shows the character of these 

 divers series to be identical, though the individual pressure- 

 coefficients show marked variation. The data of tbe third 

 series are made in connexion with the following data of 

 Table II., in which electromotive forces are measured before 

 and after the resistance measurements. As a rule, the 

 galvanometer-needle does not reach its position of equilibrium 

 at once ; the slow changes registered are probably due to 

 gradually vanishing thermal discrepancies (§ 37). 



12. Table II. gives results for the effect of pressure on 

 the electromotive force NaHg/glass/Hg. Here 6 is the tem- 

 perature of the vapour-bath, and e the observed electromotive 

 force, in volts, corresponding to the pressure 8p, when the 

 initial pressure is above 50 atmospheres (§ 10). k e — Be/e . Bp 

 is the pressure-coefficient. Five minutes were allowed per 

 observation. Special experiments showed that e decreases on 

 cooling. The medium for transmitting pressure is again 

 ordinary animal sperm-oil. Earlier observations were dis- 

 carded, and results are condensed as far as possible. 



Table II. — Apparent Effect of Pressure on the Electromotive 

 Force of NaHg/glass/Hg. 



e. 



Mean & e xl0 6 . 



dp. 



eXlO. 



10 G x* e . 



e 



Mean/r e Xl0 6 . 



dp. 



exu>. 



10 6 x£ e . 



100°. 



( ° 

 1 720 



5180 





t215°. 



1 ° 



1 488 



11182 





230. 



5950 



210 



109. 



11244 



11-3 





1 1030 



4300 









f ° 

 1 992 



11210 



. 





5440 



245 





11332 



11-0 













[1378 



11224 



— 



*215°. 



( ° 

 1 533 



10872 



— 





11374 



9-7 



7-3. 



10904 



5-5 





( ° 

 1 550 



11214 



_ 





[ ° 



\ 524 



f ° 



10912 



— 





11286 



11-7 





10950 

 10922 



6-7 











310°. 



1 505 



10658 



_ 





\ 551 



10968 



7-7 



51. 



10672 



2-5 





[1010 



10996 



6-8 





I ° 



1 480 



10666 









f ° 



10924 



— 





10706 



7-8 





\ 535 



10976 



8-9 













1 1011 



11008 



7-7 













f ° 



10924 

















542 



10972 



8-2 













1 1033 



11004 



7-2 



* Before the ) 



*esistanc€ 



-measur 



jments. 





[1441 



11024 



6-5 



t After 







j> 





f ° 



10912 



— 













540 



10968 



9-6 













1 1027 



11004 



8-3 













[1436 



11028 



7-4 











Phil. Mag. S. 5. Vol. 31. No. 188. Jan. 1891. 



a 



