6)" 



Observations on various Liquids. 237 



optical effect are sensibly proportional, and each approximately 

 a measure of the other. 



(3) As the potential increases, the intensity of the corre- 

 sponding birefringent action also increases. This is evident 

 from both Tables. 



(4) The increments of potential corresponding to a constant 

 increment of birefringent action have sensibly smaller values 

 at high than at low potentials. This is distinctly proved by 

 column K of both Tables. It shows that the intensity of the 

 optical effect varies more rapidly than the potential. Any 

 conclusion more definite would be perhaps premature at pre- 

 sent, and until the numerical results are more consistent ; but 

 the following is not without interest. 



(5) Working from a fair average of the best measurements, 

 putting v and v' for the scale-values of potential correspond- 

 ing to two consecutive birefringent actions q and q + 1 (mea- 

 sured by integer pounds of tension), and determining n suc- 

 cessively so as to satisfy a set of equations of the form 



q + 1 



q ' 



I find that the intensity of the optical effect varies more 

 rapidly than the second power of the potential through the 

 whole range of observation, but not more rapidly than the 

 third power except for low potentials. Between birefringent 

 actions 1 and 2, the value of n is slightly in excess of the 

 number 3. The average value of n for all the observations is 

 almost exactly equal to |. 



50. Measurements in other Liquids. — The method of obser- 

 vation has been already described in detail (47). The num- 

 bers in the first line of the following Table give the pounds of 

 tension in the fixed compensator ; those in the second line give 

 the scale-values of the neutralizing potential in CS 2 , and so 

 forward for the other liquids named. 



12 3 4 



Carbon disulphide 57 69 80 90 



Cumol 81 971 in 122 



Carbon dichloride 115 ... 161 



Xylol 115 137 160 



Toluol ] 



Cymol I 130± 160 + 



BenzolJ 



Amylene 145 + 



Terebene 180 + 



Benzol (bis) 105 147 176 



