1886.] A General Theorem in Electrostatic Induction. 429 

 Experimental Results (November, 1884). 



Name of dielectric. 



Distilled water . . 

 Carbon disulphide 

 Paraffin wax .... 



Naphthaline 



Lubricating oil 1 

 (petroleum?) / 

 Methyl iodide . . . 

 Oil of turpentine. 



Sperm oil 



Benzole 



Caoutchoucine . . 



Spermaceti 



Methylic alcohol . 



Amylic alcohol . . 



Chloroform 



Grlycerine 



Colza oil 



Castor oil 



Olive oil 



Cod-liver oil 



Sign of 

 electro- 

 optical 

 effect. 



Hawthorn 

 tube. 

 Sign of 



electrifica- 

 tion. 



Boxwood tube. 

 Sign of electrification. 



First set 

 of experi- 

 ments. 



Last set 

 of experi- 



Carbon 

 tube. 



Sign of 

 electrifica- 

 tion. 



To the above may be added a list of solids whose electro- optical 

 positions have been determined by Dr. Kerr. The electrical position 

 of the first two is well known. The others I examined by rubbing 

 them with the same boxwood tube as was employed in the experi- 

 ments with fluids. 



Name of dielectric. 



Glass 



Quartz 



Resin 



Sulphur 



Solid paraffin wax 



Spermaceti 



Naphthaline 



Sign of the electro- 

 optical effect. 



Sign of electrifica- 

 tion when rubbed by 

 boxwood. 



