Internal Pressure of a Liquid to its Dielectric Capacity. 

 The following are Walden's data : — 



107 



Substance. 



7r (at the 

 boiling-point). 



K (at 20° C). 



H.O 



atmospheres/cm. 2 



10600 



4000 



3100 



ca. 3800 



„ 3600 



„ 3000 



2600 



2600 



1570 



1220 



1030 



81 



>80 



ca. 95 



46 



35 



HgSC^ 



HON 



i (CH\0H) o 



CH.OH 



HCOOH 



CH 3 CN 



58 

 36 



CH 3 N0 2 



40 

 2-25 

 4-G5 

 1-85 



n.H e 



(C v H-) 2 



n H " 





Walden's values for it are doubtful, however, as be appears 

 to have calculated them by an erroneous application of the 

 Stefan principle regarding vaporization. In the following 

 table, therefore, the minimal values of it (already given) have 

 been compared with the dielectric capacity as far as data 

 could be found. The values of K are taken from the article 

 by Gr. Rudorff (Jahrbuch d. liadioakt. und Elektronik, vii. 

 p. 38, J 910), and also from Walden (Zeitsch. phys. Chem. 

 Ixx. p. 569, 1910). 



Substance. 



K. 



Temperature to 

 which Iv refers. 



7r 0°C. 



7T 



K " 





920 



91 



8 02 



60 



4315 



546 



2-322 



2-43 



2-246 



2-676 



3-2 



6-46 



23-3 



34-9 



28-4 



24-8 



80 



1°C. 



8-1° 



0° 

 14° 

 15° 



1-2° 



0° 



0° 

 17° 



0° 

 22° 

 20° 



1° 



0° 



0° 



0° 



0° 



1682 

 1389 

 1439 

 679 

 653 

 1429 

 1093 

 1144 

 1138 

 1610 

 1135 

 2307 

 1450 

 2898 

 2035 

 1601 

 6000 



182 

 152 

 180 

 113 

 130 

 260 

 471 

 470 

 507 

 600 

 355 

 357 

 58 

 83 

 72 



64 

 75 



Ethyi formate 





Ethyl propionate 



Ethyl ether 



Brombenzene 





, Toluene 



Carbon tetrachloride .. 



Carbon disulphide ... 



Stannic chloride 



Acetic acid 



1 Acetone 



Methyl alcohol 



j Ethyl alcohol 



Propyl alcohol 



Water 



i 



It is evident that there is no direct proportionality inde- 

 pendent of the nature of the substance between cohesion and 

 dielectric capacity, though the substance with large cohesion 



