112 



BELL SYSTEM TECHNICAL JOURNAL 



Data showing the variations with frequency and temperature of 

 the phase difference, dielectric constant, and their product, for several 

 materials are given in Tables I. and II. below. 



TABLE I. 



Dielectric Constant, Phase Difference and Their Product for Several Commercial 

 Insulating Materials ^ 



Material 



Frequency 

 C. P. S. 



Dielectric 

 Constant 



Phase 



Difference 



Degrees 



Product 



Phenol Fibre A 

 Phenol Fibre B 

 Phenol Fibre C 

 Phenol Fibre D 



Wood (Oak) . . . 



Wood (Maple) . 

 Wood (Birch).. 

 Hard Rubber. . 



Flint Glass. . . . 



Plate Glass . . . . 

 Cobalt Glass. . . 

 Pyrex Glass . . . 



295,000 



500,000 



670,000 



1,040,000 



190,000 

 500,000 

 675,000 

 975,000 



200,000 

 395,000 

 685,000 

 975,000 



194,000 



500,000 



695,000 



1,000,000 



300,000 



425,000 



635,000 



1,060,000 



500,000 



500,000 



210,000 



440,000 



710,000 



1,126,000 



500,000 

 720,000 

 890,000 



500,000 



500,000 



500,000 



5.9 

 5.8 

 5.7 

 5.6 



5.8 

 5.6 

 5.6 

 5.6 



5.4 

 5.4 

 5.3 

 5.2 



3.2 

 3.3 

 3.3 

 3.3 



4.4 



5.2 



3.0 

 3.0 

 3.0 

 3.0 



7.0 

 7.0 

 7.0 



6.8 



7.3 



4.9 



2.9 

 2.9 

 2.9 

 3.3 



2,2 

 2.5 

 2.6 

 2.8 



2.1 

 2.2 

 2.3 

 2.4 



4.2 

 3.9 

 3.9 

 3.8 



2.1 

 2.0 

 2.2 

 2.4 



1.9 



3.7 



.5 

 .5 

 .5 

 .6 



.24 

 .24 

 .23 



.4 



.4 



.24 



17.1 

 16.8 

 16.5 

 18.5 



12.7 

 14.0 

 14.6 



15.7 



11. 

 11. 

 12. 

 12 



22 

 20 

 20, 



19.4 



6.7 

 6.6 

 7.3 

 7.9 



8.4 



19.2 



1.5 

 1.5 

 1.5 



1.8 



1.68 

 1.68 

 1.61 



2.7 



2.9 



1.18 



'All of the samples had been in the laboratory for some time during summer 

 weather without artificial drying or other special preparation. 



