1897.] COMPOSITION OF AMERICAN PETROLEUM. 133 



ically prepared. Similar changes are produced in composition, 

 the series changing to CuH,n + .i. The series of aromatic hydrocar- 

 bons is represented in all the oils under consideration by numerous 

 hydrocarbons, beginning with mesitylene at 163°. The higher 

 homologues include cumol, pseudocumol, durol, isodurol, cymol, 

 isocymol, and doubtless other higher members. Larger proportions 

 of these bodies appear in Ohio than in Pennsylvania petroleum and 

 still larger proportions in Canadian crude oil. After the most 

 thorough purification with nitric acid and fuming sulphuric acid the 

 distillates from Ohio and Canadian petroleum have a slightly higher 

 specific gravity than the corresponding bodies from Pennsylvania 

 oil, and the hydrocarbons from Pennsylvania oil show a specific 

 gravity slightly higher than that of the hydrocarbons synthetically 

 prepared. Schorlemmer thought that these differences in specific 

 gravity were due to slight differences in isomerism, but it is quite 

 possible that these oils contain very small percentages of naphthenes, 

 especially if those bodies are slowly attacked by reagents, as Mar- 

 kownikoff observed in products from Russian oil. 

 ' If Pennsylvania petroleum, as typical of this class of crude oils, 

 is composed within the limits between 150° and 216° of the series 

 CnH2n+2, the individual hydrocarbons should resemble those pre- 

 pared by synthetic methods. Unfortunately the structure of the 

 synthetic hydrocarbons has not been determined in all instances 

 with desirable precision, although they have been obtained from 

 different sources. Normal decane boiling at 173° has a specific 

 gravity 0.7456 at 0°, somewhat lower than the decane I have sepa- 

 rated from petroleum. The boiling point of the latter body is 

 1 73°. 5, and the specific gravity at 20°, 0.7486. The decane found 

 in petroleum boiling at 163° may be diisoamyl since its specific 

 gravity after the removal of mesitylene is not very different from 

 that of diisoamyl. Its boiling point is somewhat higher than the 

 boiling point of diisoamyl assigned by Wurtz. Hendecane from 

 petroleum agrees fairly well in its properties with normal hendecane 

 prepared by Krafft from rautenol. The boiling point of petroleum 

 dodecane is the same as that of normal dodecane from laurinic acid, 

 although the specific gravity of the petroleum hydrocarbon is some- 

 what higher than the other. 



Since nothing has been done toward defining the butanes in 

 petroleum except the rather superficial examination of the most vola- 

 tile distillates in the early days of the petroleum industry, these 



PROC. AMER. rilTLOS. SOC. XXXVT. 154. J. PRINTKD MAY 20, 1S07. 



