EFFECT OF PRESSUKE ON CONDUCTIVITY OF METALS. 



121 



filled with petroleum ether. The same method would serve for any 

 other liquid which does not absorb impurity, or become conducting 

 under pressure. Unfortunately most of the liquids whose other 

 properties are best known, and which it would be most interesting to 

 measure, such as the alcohols, are not of this kind. To determine the 

 thermal conductivity' of these under pressure it will be necessary to so 

 modify the apparatus that the liquid can be insolated from the electri- 

 cal leads. 



1 2 3 4 5 6 7 8 9 10 II 12 



Pressure, Kg. /Cm.' xX I ' 

 Petroleum Ether 



Figure 13. Petroleum Ether. Thermal conductivity in arbitrary units 

 against pressure in thousands of kg/cm^. Results were obtained with the 

 apparatus of Figure 12. 



The observed results with petroleum ether are shown in Figure 13. 

 The greater regularity of the results as compared with the metals is 

 manifest. The lowest pressure of these readings was 500 kg. The 

 reason for not going to atmospheric pressure was not error from con- 

 vection currents, but because at this pressure the heating effect would 

 have been sufficient to vaporize the ether, and so introduce error. 



