20 



Mr. Carl Barus on the 



Table V. — Insulation and Pressure-Coefficient of Petroleum. 

 Initial pressure, p = 50 atm. Pressure-coefficient of 

 glass. 



Series No. 









Series No. 









e. 



R. 



10 3 X 

 3R/R. 



dp. 



10 6 xA>. 



9. 

 R. 



10 3 x 

 dR/R. 



dp. 



10 6 x/,v. 



Mean£rXl0 6 . 









Mean k r X 10 6 . 









3. 



700 



460 



1530 



Petroleum tested again. p n = 



200 atm. 



20°. 



370xl0 6 a>. 



+1500. 



700 



480 



1460 



4. 



100°. 



740xl0 6 w. 



+ 1800. 



560 



750 



370 

 360 



1500 

 2100 



3. 



100°. 

 130xlO c w. 



+820. 



520 

 570 



580 

 760 



890 

 750 



4. 

 215°. 



115 

 193 



310 

 305 



380 

 640 









64xl0 6 u>. 

 +560. 



166 

 200 



300 

 300 



553 

 667 



3. 



215°. 



40xl0 6 w. 



+274. 



134 

 167 

 177 



570 

 590 

 580 



234 

 282 

 306 



4. 

 310°. 



-115 

 -175 



300 

 550 



-383 

 -320 









32xl0 6 u>. 

 -340. 



-100 

 -105 



285 

 290 



-360 

 -360 



3. 



-285 



550 



-521 



310°. 

 f47xl0 6 w 

 \ to 



-281 

 -229 

 -223 



570 

 570 

 640 



-492 

 -404 

 -349 





— 140 

 -115 

 -130 



523 

 298 

 495 



—270 

 -383 

 -265 



[34xl0 6 «. 



-192 



520 



-369 





-105 



280 



-380 



— 430. 









Glass tube inserted. 















Glass 



tube in 



serted. 









VIII. 



630 



570 



880 



IX. 



100°. 

 10V 

 +1330. 



400 



300 



1330 



100°. 

 230xl0 6 w. 



+780. 



420 



610 



680 

















IX. 



215°. 



700xl0 3 w. 



+93. 



20 

 25 

 36 

 30 



300 

 280 

 300 

 300 



66 



88 



120 



100 



VIII. 



215°. 



200xl0 3 w. 



+ 136. 



84 

 86 



630 

 600 



132 

 142 



IX. 



310°. 



140xl0 3 a,. 



-76. 



-25 

 -32 

 -17 



300 

 300 

 300 



- 83 

 -107 



- 55 



VIII. 



310°. 

 50xl0 3 co. 



20 

 34 

 33 



740 

 725 

 665 



26 

 34 

 50 



X43. 



40 



640 



63 









The specific resistance of petroleum is not so high as that 

 of gasolene, though it is more than 20 times that of glass at 

 215°, and the insulation breaks down less rapidly. The 

 pressure-coefficients decrease in marked degree with rise of 

 temperature, and nearly proportionally to it, and they actually 

 pass from positive to negative values. They are of a larger 



