128 COMPOSITION OF AMERICAN PETROLEUM. [Feb. 5, 



of reaching satisfactory results with these bodies. In a paper 

 recently published in the Proceedings of the American Academy an 

 account is given of the composition of Pennsylvania, Ohio, Canadian 

 petroleums below 220°. The series C^Han + s represents the main 

 body of Pennsylvania and Ohio oils, and of Canadian oil below 

 195°. Aromatic hydrocarbons of the series C^Hon-e, are present in 

 considerable quantities. 



Careful study of petroleum from different sources with reference 

 to its occurrence and composition indicates that no precise classifi- 

 cation of crude oils can be based on these particular features. Ac- 

 cepting Pennsylvania petroleum as typical in its occurrence as a 

 sandstone oil, in its composition, and in the fact that it is a low 

 sulphur oil, even the numerous varieties from different sections and 

 different strata in the same field present great variations in the pro- 

 portions of the individual constituents. Such oils as the light amber 

 variety from the Berea grit sandstone (Mabery & Dunn, Amer. 

 Chem. Journ., xviii, 1896) in southern Ohio and Virginia show 

 larger proportions of volatile constituents below 150°, and those dis- 

 tilling above 250°, but less of the intermediary constituents which 

 are looked on in refining as the more valuable illuminants. In at- 

 tempting a classification with reference to the proportion of sulphur 

 compounds, it appears that the principal components of the typical 

 Pennsylvania oil form the main body of such oils as those from 

 Ohio Trenton limestone, and the Canadian Corniferous limestone, 

 although below 150°, in the limestone oils the proportions of the 

 hydrocarbons CnHjn + i are relatively smaller and the aromatic hydro- 

 carbons CnH2n_6 rclativcly larger. These statements are made on the 

 basis of results recently published (Mabery, Froc. Ajner. Acad., 

 xxxii, 131). Study of the higher portions of Pennsylvania petro- 

 leum above 220° is now in progress for the purpose of separating 

 without decomposition by distillation in vacuo, with consequent 

 diminution of boiling points and exclusion of air, the constituents 

 between 216° and 400°. This work has progressed sufficiently to 

 show that the aromatic hydrocarbons of the series CnH2n_6, form 

 only a comparatively small proportion of the distillates at least 

 within the lower limits of temperature. It should be borne in 

 mind that nothing is known concerning the principal or the subor- 

 dinate constituents of American petroleum above 250°, except the 

 possible presence of certain aromatic hydrocarbons, and these were 

 recognized in products of ordinary distillation in which there is in- 



