MABERY AND HUDSON. — REFRACTIVE POWER. 181 



purified distillates, but more uniform after purification. A comparison 

 of refractive power in the same di:?tillates from all the oils reveals higher 

 values in the Ohio and Canadian distillates than in those from Pennsyl- 

 vania oil, analogous to the differences in specific giavity referred to in the 

 preceding paper. In the unpuiilied distillate 163° from all sources, the 

 influence of the large proportions of mesitylene is apparent. 



In determining the refractive power of the monochlor and dichlor 

 derivatives of the hydrocarbons between 160° and 216°, portions of the 

 product were used whose composition was determined by analysis, as 

 shown in the preceding paper. On account of the limited quantities 

 purification was not carried as far as would have been desirable, although 

 the proportion of other bodies was probably not sufficient to affect seri- 

 ously the results. The differences in refractive power between the 

 hydrocarbons and the monochlor derivatives, as well as those between 

 the monochlor and dichlor derivatives are sufficient to demonstrate the 

 influence of the chlorine atoms. 



Monochlor derivatives : — Pa. Ohio. Can. 



Distillate 



125-130 (C10H21CI) 

 130-140 (C10H21CI) 



a ii 



145-150 (CuH.sCI) 

 140-145 (C12H25CI) 



Dichlor derivatives : — 



Distillate. 



160-170 (C10H20CI2) 



170-180 (C10H20CI2) 



<( u 



190-200 (Ci.&hCL) 



