MABERY. — THE COMPOSITION OF PETROLEUM. 579 



A determination of the index of refraction, which was found to be 

 1.4435, and the molecular refraction, correspond more nearly to the 

 formula C 18 H 36 : — 



Calculated for Found 



82.90 84.96 82.60 



A combustion of the solid hydrocarbon gave proportions required for 

 the series C n H 2n+2 : — 



0.1564 grm. of the substance gave 0.4883 grm. C0 2 and 0.2083 grm. H 2 0. 



Calculated for C l8 H 38 . Found. 



C 85.06 85.15 



H 14.94 14.80 



The position in the series was shown by its molecular weight : — 



I. 1.9475 grm. of the solid and 25.21 grms. benzol gave a rise of 

 0°.7734. 

 II. 1.9475 grm. of the solid and 25.28 grms. benzol gave a rise of 

 0°.7830. 



Calculated for Found. 



^18^38- I- !*• 



254 256 253.2 



The formula of octodecane was further confirmed by its index of refrac- 

 tion. The index was found to be, at 20°, 1.440, which corresponds to 

 the molecular refraction : — 



Calculated for C l8 H 33 . Found. 



84.96 84.53 



NONODECANE, C 19 TT 



lo- 



in the eighth distillation under 50 mm., 335 grams collected at 210°- 

 212° with much smaller weights on either side. After continuing the 

 distillation twenty-seven times, a portion of the fraction 210°-212° was 

 purified with fuming sulphuric acid ; before this treatment the oil gave 

 as its specific gravity at 20°, 0.8274, and afterward, 0.8122. In deter- 

 mining its molecular weight by the freezing point method the following 

 values were obtained : — 



