1897.] COMPOSITIOX OF AMERICAN PETROLEUM. 127 



oil, in which he subjected the various refinery distillates to a pro- 

 longed course of fractional distillations in a special form of regu- 

 lated condenser which he devised for such distillations. He sepa- 

 rated distillates at o°, 8°-9°, 30°, 37°, 6i°, 68°, 90°, 98°, ii9°.5, 

 1 2 7°. 5 and at 150°. 8, of the series CnHgn + i., and of the series 

 CnHan, members at 174°. 9, 195°. 8, 216°. 2. 



In connection with the discovery by synthesis of the hydrocarbons, 

 hexane and heptane, Schorlemmer, in 1865, separated the hydro- 

 carbons CgHi^ and C^Hig, boiling at 60° and 90°. After Warren's 

 results were published, he admitted the others at 38°, 6S° and 98°. 

 Schorlemmer also separated an octane at 125°. He corrected 

 the work of Pelouze and Cahours with reference to boiling 

 points. At about the same time in 1880, Beilstein and Kurbatiff 

 and Schutzenberger and Jonine undertook an examination of the 

 Caucasus petroleum, and identified hexahydro-aromatic compounds 

 at 97° and at 118°. The former chemists also found hexahydroi- 

 soxylol at 118° in American petroleum. Soon afterward Markowni- 

 koff separated a long series of the naphthenes at 69°, 97°, 118°. 5, 

 136°, 162°, 182°, 216°, and several members with higher boiling 

 points. Markownikoff also found numerous aromatic hydrocarbons 

 of the series C^H.^.g, and of other series with less hydrogen. 



Various examinations of lesser magnitude have been undertaken, 

 in a more or less superficial manner. Engler showed the presence 

 in small quantities of mesitylene and other aromatic hydrocarbons 

 in Pennsylvania petroleum. Among other bodies present in small 

 amounts are the nitrogen compounds, the oxygen compounds, concern- 

 ing which there is still some question as to the form in which they 

 exist in the crude oil. Recently Zaloziecky has attempted to show the 

 presence of the terpenes, which I recognized by their odor seven 

 years ago {Proc. Ainer. Acad., Vol.. xxv, 1890). I began the study 

 of petroleum in 1884, and in 1885, soon after the Trenton limestone 

 oil was discovered, I undertook to separate the sulphur con- 

 stituents. The sulphur compounds in Canadian petroleum were 

 undertaken in 1891, and are still in progress. In 1893, through aid 

 granted by the C. M. Warren Committee of the American Academy 

 of Arts and Sciences, the scope of my work was extended to include 

 broadly the composition of American petroleums with especial 

 reference to Pennsylvania, Ohio and Canadian crude oils. The 

 great field for research includes the portions of petroleum with boil- 

 ing points above 220°, but there are serious difficulties in the way 



