396 Prof. W. M. Thornton on the Polarization of 



From the readings of Table I., we have now for the latter 

 ellipsoid after 20 minutes' electrification. 



F 



•087 



•116 



•129 



•284 



•404 



•506 



•747 



FV(fc 2 -«o 2 ) 



8-8 



8-8 



8-8 



8-26 



8-8 



9-3 



8-92 



The mean of F 2 /(?i 2 — n 2 ) is 8*81, and since the derived value 

 of K depends upon this we have the remarkable fact that the 

 polarization approaches the same value irrespective of: the 

 intensity of the polarizing field. This suggests that the slow 

 polarization is a consequence of internal molecular attractions 

 started by the initial polarization and maintained to a limit 

 by the continuance of the field, but not in any way pro- 

 portional to it. This is considered further in section 7. 



Fused quartz has been largely employed in the construction 

 of electroscopes for use in measurements of radioactivity. 

 It is conceivable, though not highly probable, that some of 

 the earlier observed feeble radioactive effects may have been 

 in some measure due to the slow absorption of charge by the 

 quartz support, for the rate of charge or discharge of such 

 an instrument must be influenced by the polarization of the 

 support. 



3. Experiments on Flint Glass. 



Similar measurements to those on quartz were made with 

 flint glass specimens. 



Cylinder of density 4*6. — Free period 23*8 seconds. After 

 5 days in F = *132, period 19*5 s. ; after 48 hours longer in 

 F = -272, period 13'8. From these F 2 /(>z 2 -?? 2 ) =21*86 and 

 20*25 respectively, giving K = 580. 



Ellipsoid of density 4*1. — Free period 41*5 seconds. After 

 48 hours in F = *132, period 23*75 ; after 48 hours longer in 

 F = -272, period 12*5. Here F 2 /{n 2 -?i*) = 14*1 in the lower 

 field, 12*4 in the higher. The corresponding mean value of 

 K is 520. On a fresh suspension the following rate of 

 polarization was observed. 







Iw=8'52. 







Time 



30 s. 



2*5 in. 



4*5 m. 

 47-0 



&o m. 



19 b. 



K 



27-9 



377 



50 



200 



