MABERY. — THE COMPOSITION OF PETROLEUM. 575 



A portion of the original distillate 174°-175° was cooled to —10°, 

 which caused the separation of a crystalline mass. It was filtered cold, 

 but the solid remaining formed but a small part of the original oil. 



The specific gravity of the filtered oil 0.8005, was slightly higher than 

 the unfiltered distillate. The quantity of the solid was not sufficient for 

 analysis or further examination. No further examination was made of 

 the filtered oil, for it was evident that the small amount of solid hydro- 

 carbon could not change the composition, nor other constants, especially 

 since, as siiown above, the original distillate has the composition of the 

 series C„H2n+2- 



HePTADECANE, C17H36. 



The fraction which collected at 188°-190° after the 42d distilla- 

 tion gave as its specific gravity at 20° after drying over sodium, 0.8017. 

 After agitation with sulphuric acid it gave 0.8019, and after purification 

 with fuming sulphuric acid, 0.8000. Under 760 mm. pressure this oil 

 distilled almost entirely at 288°-289°, with very little residue above 

 289°. The small residue was badly colored from decomposition. 

 Evidently it would not be possible to distill this oil continuously under 

 atmospheric pressure in presence of air without serious decomposition. 



The formula of this distillate was established by two determinations 

 of its molecular weight and by analysis. 



I. 1.4294 grm. of the oil and 25.7086 grms. benzol gave a depression 



of 1°.17. 

 II. 1.4382 grm. of the oil and 25.6785 grms. benzol gave a depression 

 of 1°.18. 



Calculated for Found. 



C17H38. I. II. 



240 241.2 240.9 



Analysis I. was made of the unpurified oil dried over sodium, and 

 Analysis II. after purification with fuming sulphuric acid. 



I. 0.1534 grm. of the oil gave 0.4778 grm. CO2 and 0.2044 grm. HjO. 

 II. 0.1491 grm. of the oil gave 0.4641 grm. CO2 and 0.2014 grm. H2O. 



