MABERY. 



CONSTITUENTS OF PETEOLEUM. 



143 



Pennsylvania C„IIo„+2 : — 



Another important result of this study is the evidence that the main 

 body of the hydrocarbons in Pennsylvania petroleum within these limits 

 of temperature are members of the series C„H2„+o. Satisfactory analytical 

 data in proof of this conclusion have cost a vast expenditure of time and 

 effort, not only in the routine labor of separation and purification, but in 

 obtaining suflficiently close percentages of carbon and hydrogen. In such 

 a larfre number of determinations the ordinary method of combustion be- 

 comes exceedingly tedious, since all details must be vpatched with the 

 oreatest care. In the beginning of analysis there was not the slightest 

 evidence as to whether the hydrocarbons were of the series C,jIl2„+2» 

 or of the series C„Ho„. The extreme hygroscopic nature of these 

 bodies was not then appreciated, nor the refinement in purification neces- 

 sary to yield acceptable results. Many analyses were made before these 

 details were fullv understood. 



Constituents of Ohio Trenton Limestone Petroleum. 



The constituents of Ohio petroleum between 160° and 216° were sought 

 for in vacuum distillates obtained from the crude oil, as described in a 

 former paper.* 



Distillation in vacuo was continued until all portions had collected 

 that could be brought together within the desired limits. Further con- 

 centration was carried on under atmospheric pressure, since this did not 

 occasion serious decomposition. Probably no petroleum distillates with 

 such high boiling points can entirely escape decomposition in a long 

 course of distillations, but small amounts of decomposition products can 

 DO doubt be removed by sulphuric acid, leaving the main body of the oil 

 free from contamination. After the first distillations in vacuo Ohio 

 distillates seem to suffer no more change during distillation than those 

 from Pennsylvania oil. Before separation into two degree fractions, the 

 sulphur compounds were removed so far as possible by precipitation with 

 mercuric chloride. As the distillation proceeded, the characteristic 



* Proc. Amer. Acarl., XXXT. 2-5. 



