92 PROCEEDINGS OF THE AMERICAN ACADEMY. 



fraction has corresponded in boiling point to that of the fraction before 

 separation, it has been possible to select from the great number of 

 first fractions those which should give the bodies desired, thereby sav- 

 ino' much time and unnecessary labor in searching for the individual 

 constituents. 



After the second precipitation from the mercuric chloride compound, a 

 few distillations in vacuo, with the aid of a bead column in a long-necked 

 flask, have been sufficient to bring together, for the most part, within one 

 or two degrees, the sulphur compound desired. For the separation with- 

 out decomposition of the sulphur oils boiling above KiO°, distillation 

 in vacuo has been indispensable. Doubtless exclusion of air, as well 

 as the reduction in boiling points, especially of the higher members, is 

 essential. 



The most volatile vacuum distillates 4(T-50° were subjected to eight 

 additional distillations within limits of two degrees, and oOO c.c. of 

 these distillates was agitated with an excess of alcoholic mercuric chlo- 

 ride. A part of the oil was immediately converted into a crystalline 

 precipitate, and the sulphur-free oil, which formed the greater part of the 

 oil taken, remained entirely in solution and was separated by dilution. 

 After decantation of the alcoholic solution, the crystalline precipitate was 

 well washed with alcohol and light gasoline, and decomposed by hydric 

 sulphide in presence of alcohol. 



For complete removal of the sulphur-free oil the mercuric chloride 

 compound was again formed, washed, and the sulphur oil separated by 

 hydric sulphide. Unfortunately, the larger portion of the sulphur oil 

 was accidentally lost, but the remainder was fractioned, so far as possible, 

 until finally it showed a tendency to collect at 125°-] 30°. 



The percentage of sulphur found in this product was 27.12 ; required 

 for the sulphur compound C G H 12 S, 27.60. The crystalline condition of 

 this substance is characteristic of the alkyl sulphides ; but all the sulphur 

 bodies we have separated from petroleum are viscous oils that could not 

 be solidified, except the more volatile sulphur compounds such as were 

 separated from Ohio petroleum, which were crystalline. 



The following series of sulphur compounds which have been identified 

 by analysis, and shown to have the composition of the general formula 

 C n H 2n S, do not represent any series known. They are not members of 

 the ethylene sulphide series, as shown by their reactions and very high 

 spec'fic gravity. In empirical composition they correspond to hydro- 

 thiophenes, which have not been synthetically prepared. 



