MABERY AND QUAYLE. — CANADIAN PETROLEUM. 99 



The thiophanes still further resemble the well-known series of sulphur 

 derivatives in their behavior toward oxidation. The formation and 

 properties of the sulphones will be described later. 



In addition to the analytical data that establish the composition of 

 the thiophanes, we have determined their indices of refraction, and 

 the corresponding molecular refraction verifies the formulas given by 

 analysis. 



Indices of Refraction of the Thiophanes. 



Many attempts were made to determine the molecular weights of 

 the sulphur compounds in Canadian petroleum with different solvents, 

 but no concordant values could be obtained, even with the same substance 

 and the same solvent. 



Better success, however, was reached in ascertaining the indices of 

 refraction. But since the values for sulphur in organic compounds 

 have not been determined with the same certainty as in the case of 

 carbon, hydrogen, and oxygen, some attention was given to verifying this 

 constant. 



The index of refraction found by Nasini for ethyl sulphide was 

 1.44233; for ethyl mercaptan, 1.43055; and for ethyl disulphide, 

 1.50633. 



Assigning the accepted values to carbon and hydrogen, the calculated 

 value for sulphur becomes, for ethyl sulphide, 7.98 ; for ethyl mercaptan, 

 7.81 ; and for ethyl sulphide, 8.03. In determining the value of sulphur 

 in ethyl mercaptan, we fouud the angle to be 49° 24', which corre- 

 sponds to the index 1.4323, and the calculated value for sulphur is 7.89. 



Isobutyl sulphide gave us 1.4585 as its index of refraction, calculated 

 from the observed angle 44° 57' ; the corresponding molecular refraction 

 is 46.85. Assigning the accepted values to carbon and hydrogen, the 

 difference is the value of sulphur, 7.98, the same as the value calculated 

 from jSasini's index of ethyl sulphide. 



The index assigned to thiophen is 1.5268, which gives as its molecular 

 refraction, 24.12, leaving a value for sulphur 6.53. Thiophen is assumed 

 to have two sets of double bonds. The petroleum sulphur compounds 

 under consideration, although doubtless possessing a ring structure, 

 apparently do not contain carbon atoms connected by double linkage. 

 We have therefore considered it safe to use the value 7.98 for sulphur, 

 and the following molecular refraction for the petroleum sulphur com- 

 pounds were calculated on the basis of this value. 



