MABERY. — ON THE COMPOSITION OF PETROLEUM. 355 



As formerly explained, the freezing point of benzol cannot be relied 

 on for solids with molecular weights much above CoqHio. At its boiling- 

 point benzol can be depended on for a somewhat higher range, but 

 becomes uncertain with hydrocarbons in the vicinity of CaoHoa- Other 

 solvents are equally uncertain, on account of a lack of solubility or un- 

 certain influence of the dissolved substance on the freezing point. After 

 long trial with naphthaline, which promised reliable results on account 

 of its free solvent power and large depression, we found that the sub- 

 stances that had melting points not far removed from that of naphthaline 

 gave variations in depression too great for reliable calculations of molec- 

 ular weights. 



Solid Hydrocarbons in Pennsylvania Oil Wells. 



Hydrocarbons of the series CnFIo„+2 have now been identified in Penn- 

 sjdvania petroleum in continuous series, with but few members wanting 

 from butane, CJlio, B. P. —10^ to i^entatricoutane, C35H72, B. P. 380°- 

 384°, 50 mm. 



VI. COMPOSITION OF COMMERCIAL PARAFFINE.* 



It has been questionable, even with refiners of petroleum of long ex- 

 perience, as to whether paraffine is actually present in the crude oil 

 or whether it is a result of change during the process of refining. It 

 therefore seemed of interest to ascertain whether the hydrocarbons of 

 which commercial paraffine is composed are identical with the solid con- 

 stituents of the crude oils that yield parafRne. 



The method of distillation was the same as that employed in distilling 

 the crude oil, except that it was found necessary to pack the neck of the 

 flask with a thick coating of asbestos. With exclusion of air it was found 

 that parafRne could be distilled indefinitely with no decomposition. But 

 introduction of air, either by leaks or by accident, caused serious decom- 

 position, as shown by the dark color and disagreeable odor of the dis- 

 tillates. 



* A part of tlie work described in this paper was performed by Mr. II. R. 

 Payne, and formed tlie subject of a thesis for the degree of Bachelor of Science. 



