188 7. J Specific Inductive Capacity. 159 



No. 1, This oil was kindly procured direct from Italy for these 

 experiments by Mr. J. C. Field, and was tested as supplied to me — 



K = 3-10. 



No. 2 was purchased from Mr. Sugg, and tested as supplied — - 



K = 3-14. 



No. 3 was purchased from Messrs. Griffin, and was dried over 

 anhydrous copper sulphate — 



K = 3-?3. 



No. 4 was refined rape oil purchased from Messrs. Pinchin and 

 Johnson, and tested as supplied — 



K = 3-08. 



No. 5 was the same oil as No. 4, but dried over anhydrous copper 

 sulphate — 



K = 3-07. 



No. 6 was unrefined rape purchased from Messrs. Piuchin and 

 Johnson and tested as supplied, the insulation being bad, but still not 

 so bad as to prevent testing — 



K = 312. 



No. 7. The same oil dried over sulphate of copper — 



K = 3-09. 



Omitting No. 3, which I cannot indeed say of my own knowledge 

 was pure colza oil at all, we may, I think, conclude that the specific 

 inductive capacity of colza oil lies between 3*07 and 3*14. 



Professor Quincke gives 2*385 for the method of attraction between 

 the plates of a condenser, 3*296 for the method of lateral compression 

 of a bubble of gas. Palaz* gives 3*027. 



Olive Oil. — The sample was supplied me by Mr. J. C. Field — 



K = 3*15. 



The result I obtained by another method in 1880 was 3*16. 

 Two other oils were supplied to me by Mr. J. C. Field. 

 Arachide. — K = 3*17. 

 Sesame. — K = 3*17. 



A commercial sample of raw linseed oil gave K = 3*37. 



Two samples of castor oil were tried ; one newly purchased gave 



* ' La Luuuere filcctrique,' vol. 21, 188G, p. 97. 

 VOL. XLIII. N 



