156 PROCEEDINGS OF THE AMERICAN ACADEMY. 



"While, therefore, the formula of dodecane iu Ohio petroleum is uot 

 suj^ported by such reliable data as those of the lower constituents the 

 presence of this hydrocarbon is established, I think, beyond question. 



The principal constituents of Ohio petroleum have been shown to be 

 identical with those of Pennsylvania petroleum. The higher specific 

 gravity and peculiar qualities of the Ohio distillates depend on the 

 larger proportions of aromatic hydrocarbons, and perhaps of other 

 heavy constituents. 



Constituents of Canadian Petroleum from the Corniferous 



Limestone. 



In continuing the study of the higher portions of Canadian petroleum, 

 the vacuum distillates 150°-300°* were carried through fifteen addi- 

 tional distillations under 50 mm. As the separations proceeded, the 

 fractions fell 50° or more in boiling points, large portions collecting 

 below 220°, the point where the separations could be continued without 

 serious decomposition under atmospheric pressure. In single degree 

 fractions after the fifth, distillation w^as continued until the operation 

 had been repeated in all twenty-nine times. As in the other oils, the 

 distillates collected mainly at 159°-16r, 168°-170°, 188°-19r, and 

 208°-210° (730 mm.). There is even greater necessity in the Canadian 

 than in the Ohio oil that the earlier distillations be carried on in vacuo, 

 on account of the greater quantity o£ sulphur compounds, but more 

 especially, as will be seen in another paper, on account of the greater 

 proportion of unsaturated hydrocarbons and the smaller proportions of 

 the members in question that distill between 160° and 216°. It is, there- 

 fore, otherwise impossible to obtain a large proportion of these higher 

 constituents uncontaminated by impurities due to cracking. But the 

 vacuum distillates are free from the intensely disagreeable odors due 

 to cracking, which are far more pronounced than any to be obtained from 

 Ohio oil. Nevertheless, the natural odor of these compounds, however 

 carefully they have been protected from decomposition before purifica- 

 tion, is more pungent than those from Ohio oil. Colorless when first 

 distilled, all these distillates become colored on standing, probably on 

 account of polymerism of the unsaturated hydrocarbons alluded to above, 

 and of other unstable bodies resembling the terpenes, which we have 

 good evidence are contained in petroleum. That this is unquestionably 

 the cause of the coloration w^e have abundant evidence iu the polymeri- 



* Proc Amer. Acad., XXXI. 52. 



