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 CisHgo : — 



Calculated for vn„„A 



r TT r IT Jjouna. 



82.90 84.96 82.60 



A combustion of the solid hydrocarbon gave proportions required for 

 the series C^U-i^+o- — 



0.1564 grm. of the substance gave 0.4883 grm. CO.j and 0.2083 grm. H.^O. 



Calculated for CijHjj. 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. 



CsU-s. I. II. 



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 CigHja. Found. 



84.96 84.53 



NONODECANE, C19H40. 



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 2 10° -2 12° 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 : — 



