OF ARTS AND SCIENCES. 225 



0.0443 gr. of the substance gave 0.0880 gr. BaSO^. 



Calculated for (CjHjjjS. Found. 



27.12 27.44 



The presence of propyl sulphide was further shown by analysis of 

 the platinum salt. 



I. 0.1720 gr. of the salt gave 0.0600 gr. Pt. 



11. 0.1309 gr. of the salt gave 0.0457 gr. Pt. 



III. 0.0930 gr. of the salt gave 0.0329 gr. Pt. 



Pt 



Analyses II. and III. were made of preparations from fraction 80 — 

 90° (P = 150 mm.) that were obtained in fractioning the oil from 

 the sulphuric acid extract. This oil contained only very small quan- 

 tities of propyl sulphide, or of other lower horaologues. It consisted 

 mainly of higher sulphides and of sulphur free oils. The presence of 

 heptyleu has been described, and nearly all fractious contained sul- 

 phur free oils that united readily with bromine, and those of lower 

 boiling points with hydrobromic acid. The sulphides were separated 

 by dissolving the oil in alcohol, and adding a small excess of alcoholic 

 mercuric chloride. An aqueous solution precipitates the sulphides, 

 but it is apt to carry down the sulphur free oil. The precipitates 

 were usually in the form of a thick viscous mass, although with care 

 they could be obtained crystalline. They were washed with alcohol, 

 and decomposed by hydric sulphide in presence of alcohol. The 

 filtered alcoholic solution was diluted with water, and the sulphide 

 that separated was washed free from hydric sulphide, dried, and again 

 submitted to fractional distillation for analysis. 



Upon dilution of the alcohol from the precipitation by mercuric 

 chloride, an oil separates that is lighter than water, and with an ex- 

 ceedingly disagreeable odor. These oils unite readily with bromine 

 and with hydrobromic acid, and they contain no sulphur. "Whether 

 they are decomposition products resulting from the action of sulphuric 

 acid upon the sulphur oils, or are normal constituents of the crude 

 petroleum, we have not fully determined. But since the sludge acid 

 showed very little indication of decomposition, it seems probable that 

 the sulphur free oils are abstracted by sulphuric acid during the 

 process of refining. 



The composition of the fractioned sulphides before and after treat- 

 ment with mercuric chloride may be shown by the effect on the 



VOL. XXV. (N. S. XVII.) 15 



