MABERY. — THE COMPOSITION OF PETROLEUM. 589 



These percentages evidently support the formula C 2 4H 48 . 

 A determination of the molecular weight of the liquid hydrocarbon 

 gave at the boiling point of benzol a result required for C 24 H 48 . 



2.0681 grms. of the oil and 25.78 grms. benzol gave a rise of 0°.G096. 



Calculated for C^H^. Found. 



336 337.4 



The index of refraction of the oil was found to be 1.4726, from which 

 the following molecular refraction was calculated : — 



Calculated for Co 4 II 18 . Found. 



110.47 109.75 



Specific gravity of the oil at |§°, 0.8582. 



The solid separated by filtration melted at 48°. Krafft's hydrocarbon, 

 C 24 H 48 , melted at 51°. It gave as its specific gravity the following 

 values : — 



60°, 0.7902 70°, 0.7893 80°, 0.7875 



With water at 4° these results reduce to 0.7742. The specific gravity 

 given by Krafft to tetracosane at 4° was 0.7784, the same as that of 

 the solid hydrocarbon which he separated from shale oil. The solid 

 products from Pennsylvania oil show only slight variations in specific 

 gravity. But the heavy oils show a decided increase in specific gravity 

 with increase in molecular weight. 



A combustion gave percentages of carbon and hydrogen required for 

 the series C n H 2n+2 . 



0.1433 grm. of the solid gave 0.4479 grm. C0 2 and 0.1895 grin. H 2 0. 



Found. 



C 85.70 85.23 85.25 



H 14.30 14.77 14.70 



The molecular weight was determined at the boiling point of benzol. 



Calculated for C^H^,. Found. 



338 337 



To ascertain whether the solid which separated at ordinary tempera- 

 tures was identical with what remains in solution, a portion of the oil 



