8 PROCEEDINGS OF THE AMERICAN ACADEMY. 



above 300°. To this substance was assigned the formula C32TI22- 

 Prunier and David * stated that they had obtained evidence of the 

 I^resence in refinery residues of anthracene, chrysene, pyrene, phenan- 

 tiirene, chrysogene, retene, benzerythrene, fluoanthrene, parachrysene, 

 paraanthracene, an isomeric acenaphtylene, besides different parafilnes 

 and stilbene. In the " petrocene " and " carbopetrocene " prepared 

 from the tarry residue of petroleum, Prunier and David identified 

 compounds, the former melting at 1G0°-190°, the latter at 200°-238°, 

 and also thallene melting at 110°. They attributed the green fluo- 

 rescence in petroleum to the presence of chinones. Inasmuch as these 

 products were obtained from the distillation of tar in coking, evidently 

 no inference is permissible concerning their presence in the crude oil. 

 From " petrocene," Sadtler and McCarter f separated two hydrocar- 

 bons, one of which melted at 280° and the other at 178°. From these 

 hydrocarbons the chinones were prepared, and from one an alizarine. 



In undertaking an examination of the Ohio and Canadian sulphur 

 oils with the advantage of former experience in studying the sulphur 

 constituents, it was evidently necessary to conduct the distillations 

 with all possible precautions to avoid decomposition. The tendency 

 of the sulphur oils to decomposition by heat is due as much at least 

 to the action of air on the hot oil as to the increased temperature. 

 Markownikoff and Ogloblin attributed the decomposition in the dis- 

 tillation of the Russian oil to polymerization of the unsaturated com- 

 pounds, and perhaps also to the polymerization of certain aromatic 

 compounds, such as phenylacetylerie, and they found that coloration of 

 distillates on standing was less marked when the oxygen compounds 

 had been removed. This tendency towards polymerization in unsatu- 

 rated hydrocarbons separated from sulphuric acid solutions was ob- 

 served by me, t and it will receive further attention. It was there- 

 fore deemed advisable to carry on all distillations from the crude oils, 

 instead of relying upon refinery products, except only the most vola- 

 tile distillates, and the advantage gained has been apparent in subsid- 

 iary distillations of refinery oils which had been subjected to the 

 decomposition incident to refinery distillation. Longer time is then 

 necessary for separations, and the odor of decomposition is retained 

 indefinitely during subsequent distillations. Certain constituents of 

 the sulphur petroleums are even more unstable than the suljjhides, as 



* Bull. Soc. Chim., [2.], XXXI. 158. 

 t Amer. Chem. Jouru., 1879, p. 30. 

 t Ibid., 1893, p. 92. 



