Chemical Equilibrium of Solids. 19 



liquids. For obvious reasons I selected the hydrocarbon oils 

 of the paraffin series. 



15. Table IV. contains data for the insulation and pressure- 

 coefficient of very volatile gasolene. 



Table IV. — Behaviour of Gasolene under Pressure. Initial 

 pressure, p = 200 atm. Resistance at 20°, 2 x 10 9 a>. 



. Series No. 









Series No. 









9. 



E, 



10 3 X 

 £R/K. 



dp. 



10 G Xk r . 



0. 



10 3 X 

 £R/E. 



Sp. 



10 6 xk r . 



Mean k r X 10 6 . 









Mean kr X 10 6 . 









2. 







250 







2. 



-380 



250 



-1500 



100°. 









310°. 



-550 



300 



-1800 



( 450xlC 6 w 









220 x10V 



-580 



300 



-1900 



i to 



[ 130 x10 V 









-1800. 



-550 



300 



-1800 











-590 



300 



-2000 



±0. 

















2. 



-330 



250 



-1300 



215°. 



-290 



280 



-1050 











f220xlG 6 o> 



-200 



280 



- 710 











\ to 



-140 



220 



- 640 











[loOxlOV 



-190 



250 



- 760 











-890. 

















The resistance of gasolene is therefore enormous as com- 

 pared with sperm-oil, and above 100° more than 100 times 

 that of glass. Moreover the breakdown of the gasolene 

 insulation with temperature is remarkably slow ; but owing 

 to the difficulty of keeping the apparatus free from leaks 

 in the case of this very thin oil, I did not make experiments 

 with the glass tube. 



A feature of these results is the negative pressure- coeffi- 

 cients found, which themselves decrease algebraically nearly 

 proportionally to the temperature of the oil. At a given tem- 

 perature the resistance is not constant, but decreases; and 

 since the gasolene is discoloured when removed from the 

 press, the decrease of resistance is undoubtedly a solution- 

 phenomenon. Indeed, I suspect that negative coefficients are 

 possibly to be associated with solution (§ 39). 



16. In Table V. data are given for ordinary illuminating 

 oil (petroleum). The glass tube still has the form of fig. 1, 

 reversed. Two sets of experiments were made. 



C 2 



