446 Hormell — Dielectric Constant of Paraffins. 



one may apply Cauchy's formula and thus obtain the index for 

 infinitely long waves. When the constants A and B of this 

 formula are eliminated, it takes, according to Gordon,* the 

 following form : — 



^oc^^^xr where . 



ix = index of refraction for infinitely long waves 



X = 00 



jx = " " " a given long wave 



fi x = " " " a shorter wave 



A and A represent the corresponding wave lengths. 







Table VII. 







fii for 



fj-2 for 



/J-o for 



[i\ for 



/A for 



l-i'o for 



_ 81-64 cm . 



A=41-64 cm . 



X = CO. 



Dj line. 



F line. 



A= 00. 



1-46(2) 



1-48(8) 



1-45(6) 



1-5380 



1-5567 



1-498 



1*47(3) 



1-50(4) 



1-46(2) 



1-5430 



1-5589 



1-509 



1-48(3) 



1-50(2) 



1-47(7) 



1-5505 



1-5665 



1-513 



1-49(0) 



1-51(2) 



1.48(5) 



1-5523 



1-5684 



1-519 



Table VII shows the results obtained from the application 

 of this formula to the light indices and also to the electrical 

 indices. The values of the sixth column should agree with 

 those of the third. They should at least be less than the index 

 found for the longest wave. This formula does not appear to 

 fit the experimental facts. 



Conclusions. 



1. For reversals as high as 800,000,000 per second the veloc- 

 ity of electrical disturbances along magnetic and non-magnetic 

 wires of different diameters is the same, thus showing that the 

 magnetic properties of iron are not able to follow such rapid 

 changes. 



2. The effective field around the Lecher wires as far as it 

 can be detected by means of an argon tube, does not extend 

 more than 3 cm from the wires, and the effect on the half wave 

 within this region varies approximately inversely as the square 

 of the distance from the wires. 



3. The dielectric constant of a given paraffin increases with 

 the density of the paraffin. It increases rapidly from a tem- 

 perature 20° above the melting point to a temperature 30° 

 below the melting point. Among different paraffins the dielec- 

 tric constant increases as the melting point of the paraffin 

 increases. 



4. The dielectric constant increases as the wave length 

 decreases. It is greater for short light waves than it is for 

 short electrical waves. Cauchy's formula as a means of obtain- 

 ing the index of refraction for indefinitely long waves does not 

 meet the experimental facts. 



Jefferson Physical Laboratory, Harvard University. 



* Philosophical Trans., pt. I, p. 441, 18T9. 



