200 Mr. E. B. Rosa on the Specific 



Following are the means of several such series, made in 

 the order given : — 



Table X. 



No. 







Double Deflexions. 



1. 



D.W.H. Oil 29-8 volts. 





1*450 cms. 





2. 





Air, 43-8 volts. 





1-482 



3. 





do. 





1-473 



4. 





do. 





1-472 



5. 



do. 





1-438 





6. 





do. 





1-471 



7. 



do. 





1-430 





8. 



do. 





1-436 









Means 



1-438 



1-474 





Each of the numbers given in the columns of deflexions is 

 the mean of several separate measurements. 

 We have : — 



in air, F = A£V 2 , 

 and in oil, F^AK^ 2 , 



where F and Fj are the forces in air and oil respectively, 

 V and Vi the potentials, A is a constant, K x = specific induc- 

 tive capacity of the oil, and k=l. 



_F X V 2 _ 1-438 Z43-8 



Ki = ^J. 



■GHT-* 



F ' Vi 2 1-474 



at 24° C, the specific inductive capacity of Diamond White 

 Headlight Oil. 



Water. 

 The means of three series of measurements of the force 

 for 19-8 volts at 25° were 11-88, 11-80, 11-89. Mean = 

 11-86=F. Mean for 44'8 volts in D. W. H. Oil = l'69 = F 1 . 

 K _ K F V, 2 _ 11-86 /44-8\ 2 _ 



specific inductive capacity of Water at 25° 0. 



The following is a list of several liquids with the corre- 

 sponding values of K determined in this manner : — 



Values of K for Liquids. 



Water at 



25° C. 



75-7 



Alcohol 



25° 



25-7 



Sperm oil 



20° 



3-09 



Benzine 



21° 



2-45 



Turpentine, commercial 



18°-6 



2-43 



" Neutral " petroleum . . . 



21° 



2-26 



D. W. Headlight oil ... 



24° 



2-11 



