Dielectrics in a Steady Field of Force. 



395 



wartz ellipsoid cut parallel to the optic axis 

 S—3013, V = -0534c. a, I=-02912, K =4'60. 



For a q\ 

 L = 6-133, N 



From the later set o£ observations given above n 2 = *0100> 

 in a field '266, n*= -00083. Thus F 2 / (n 2 -n 2 )= 7*25 and 

 a = 3*069, giving finally K = 508. (Quartz II ). 



In the weaker field, F = -137, F 2 /(?i 2 — ?? 2 ) =7*16, giving 

 K = 610. 



An ellipsoid of quartz cut perpendicular to the axis had 

 L = 6-125, N=-313, T=-056, I = -0307, K =4-f>48. 



Its free period was 33 seconds. After exposure to a field 

 0'26 for 48 hours the period was 19'3 seconds ; after 41 

 hours longer in a field 0*132, 26-75 seconds. 



From these we have the steady values 



F 2 / (n 2 -rc 2 )=38-5, F=0-26, 

 = 30-4, F = 0-132. 



a = -6705, and K=ll-66. (Quartz 1). 



Thus both in alternating and direct fields quartz || has the 

 larger values, but whereas in the former the ratio of the 

 dielectric constants is 1'012, in the latter it is about 45. 



For the purpose of section 6 infra, it is necessary to 

 know not only the final values but the rate of growth of the 

 polarization. The following observations show the exceed- 

 ingly slow rate of polarization of quartz J_ compared with 

 quartz II . 



The intensity of the field in all the case- given in the 

 paper not otherwise stated was about "265 electrostatic unit. 



Quartz J_. 



K — = 



=4-548 



Free 



period T = 11-82 s. 



Time 



15 s. 



35 s. 



50 s. 



16 iu. ' 120 m. 



48 h. 





Period 



11-2 

 473 



1105 

 5*2 



1102 

 509 



110 1057 



7-55 10-92 



* 



11-66 







Quartz 



II. K- = 



4-00. 



T =63-3s. 





Time 



lm. 



• ) 



4 



6 



10 



15 m. 



120 h. 



Period 



K 



17-2 



20 



15-8 



27 3 



146 



30 



132 

 53 



120 



7S 



11-4 



110 



* 



610 



* On another suspension. 



