Constants of certain Organic Bodies at Low Temperatures. 365'. 



XIII. Ethyl Nitrate (C 2 H 5 N0 3 ). 



Corrected galvanometer deflection when the condenser had air as 

 dielectric = 4*34 cm. for 100 volts. 



Temperature in 

 platinum degrees. 



-203-8 



-190-0 



-188-4 



Mean galvano- 

 meter deflection 

 in cm. 



12-25 

 12-33 

 1305 



Dielectric 

 constant. 



2-73 

 2-75 

 2-92 



Observations. 

 Condenser charged 

 to 99-8 volts. 



XIV. Castor Oil. 



Corrected galvanometer deflection when the condenser had air 

 dielectric = 4*13 cm. for 100 volts. 



Mean galvano- 



Temperature in meter deflection Dielectric 



platinum degrees. in cm. constant. 



-197-7 9-30 2-19 



-1383 - 975 2*31 

 + 20-0 17-5 4-23 



Observations. 

 Condenser charged 

 to 98-2 volts. 



XV. Olive Oil. 



Corrected galvanometer deflection when the condenser had air as- 

 dielectric = 4 - 13 cm. for 100 volts. 



Mean galvano- 



Temperature in meter deflection Dielectric 



platinum degrees. in cm. constant. Observations. 



— 147-2 9-2 2-18 Condenser charged 



+ 20-0 12-0 2-86 to 98*2 volts. 



The observations on castor oil, olive oil, and bisulphide of carbon 

 are of considerable interest. 



In the first place they show that the method we are using gives 

 results at normal temperatures which are in agreement with those of 

 other observers. Thus Dr. J. Hopkinson* found the dielectric 

 constant K of carbon bisulphide at 20° C. to be 2*67 : we find it to be 

 2*64. The square of the refractive index of carbon bisulphide for the 

 D raj at 10° C. is 2'673, and accordingly this body is generally 

 said to be one of those which obey Maxwell's law, in that its 

 refractive index is nearly equal to the square root of the dielectric con- 

 stant. If, however, we calculate the square of the refractive index of 

 bisulphide of carbon for waves of infinite wave-length using at least 



* See 'Boy. Soc. Proc!,' vol. 13, p. 161, 1887. 



