Chemical Equilibrium of Solids. 



21 



order of numerical magnitude than the glass-coefficients. At 

 310°, where the petroleum-coefficient is negative and the glass- 

 coefficient, according to Tables I. and III., positive, a crite- 

 rion of the effect of the oil is obtainable. The glass tube \ 

 does not stand tins test fully, since the pressure-coefficients of 

 oil and glass in series IX. are both negative, though the effect 

 of the glass is a decided algebraic increase of the oil-coeffi- 

 cient. Moreover, as the trustworthiness of a tube like fig. 1 

 reversed is no longer vouched for, I made the remaining ex- 

 periments with the tube figure 3. I also tested a better insu- 

 lating oil. 



17. Tables VI. and VII. contain data for the insulation 

 and resistance of thin mineral machine-oil (" mineral sperm "), 

 and also for glass surrounded by it. At 215° the resistance 

 of the liquid is more than 50 times that of glass, and the 

 breakdown in the former case much less rapid. Two glass 

 tubes of the form fig. 3 were used consecutively. In the 

 first of these the internal and external diameters of the inner 

 tube were '24: and '34 centim. respectively ; in the other the 

 dimensions of the inner tube were those given in § 5. 



Table VI. — Pressure-Coefficient and Insulation of thin Mineral 

 Machine-oil. p =150 atm. Insulation at 20 c 



*°, 3 x 10 9 o>. 



Series No. 









Series No. 









0. 



10 3 x 



§p. 



k r xl0 6 . 



E. 



10 3 X 

 £R/R. 



dp. 



k r xio e . 



Mean k r X 10 6 . 









Mean k r X 10 6 . 





370 



+260 



5. 



400 



410 



970 



5. 



95 



215°. 



400 



420 



960 



t310°. 



95 



340 



280 



320xl0 6 o>. 









50xl0 6 w. 



140 



400 



350 



+960. 









+300. 



125 



400 

 400 



390 

 410 

 420 



320 

 970 

 960 



5. 



-220 



410 



-525 





*215. 



-160 



430 



-370 











110xl0 6 w. 



-190 



440 



-430 











-440. 

















* Dirty, after an explosion. 



t Clean, refilled. 



t I strongly suspect that some oil had worked itself down into the 

 sodium amalgam, and that this is the true cause of the exceptional be- 

 haviour referred to in the text. This inference was sustained "by a 

 dissection of the tube after the experiment. 



