Chemical Equilibrium of Solids. 



33 



measure are given as ordinates. They are therefore inversely 

 proportional to the resistance of the glass. The abscissae are 

 times, supposing that the times consumed in making each 

 triplet of observations are equal and similar. The oscillations 

 are due to the fact that pressure is raised from about 150 

 atmospheres to about 600 atmospheres, and then lowered to 

 the first value again, thus giving the three points for each of 

 the triplets numbered. 



Figs. 7, 8, 9. — Charts showing the Oscillation of the Electric Conductivity 



of Glas? with pressure, at 215°, 310°, and again at 215° respectively. 



Experiments made consecutively. 

 Figs. 10, 11. — Charts showing the Oscillation of the Electric Conductivity 



of verv viscous Hydrocarbon Oil ("mineral machine-oil ,? ) with pressure, 



at 215° and 310° respectively. 



101) 



000 



800 



'00 



600 



6 

 Fig-. 10. 5 / \ 



6 01C° / \ 



\/ VYY " 



i 2 



2 



700 ' A 





600 



t 



/ F^.11. 



\ 500 



h- 



\/\ Fie- 7 



1 



40 



? \ "i r ° 



\ 30 



3 V ;.■■'.......' 



4 



■ \ glass 

 '" Fig-,8. ( 



1 2 .3 4. . 



t Y\ ■ 



— v time 



* y\/vvw-- 3irf 



In figs. 10 and 11 similar results are given for thick mineral 

 machine-oil. In the former, pressure was twice increased 

 from about 160 to 980 atmospheres and back again ; and then 



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



