172 PROCEEDINGS OF THE AMERICAN ACADEMY. 



table how closely the distillates from Pennsylvania petroleum analyzed 

 by Warren resemble in specific gravity the unpurified distillates described 

 in this paper. 



Fraction. Fraction. Specific Gravity. 



Unpurified. Purified. Mabery. Warren Series. ■ 



163°-164'' 0.7674 (20°) C^H^,, 



173°.5 0.7502 (20°) CJi^,, 



173°.5 0.7445 (20") C„H2„+, 



175° 0.7598 (15°) C„H2„ 



196° 0.7673 (20°) C^Hj^ 



196° 0.7581 (20°) C„H2„+2 



196°-197° 0.7721 (15°) C„H2„ 



216° 0.7745 (20°) CJI2,, 



216° 0.7684 (20°) C„H2„h.2 



214°-216° 0.7804 (15°) C„H2„ 



Warren found no single body at 162° ; his other hydrocarbons correspond 

 in boiling pouits vrith those described in this paper. The series C„H2„ of 

 Wai'ren, with a series of the same numerical composition in Russian 

 oil, led to the suggestion that the naphtenes might form an essential part 

 of Pennsylvania oil. This belief was encouraged by statements that 

 found their way into works on petroleum, that MarkownikofF discovered 

 the naphtenes also in Pennsylvania oil. The statement that Mar- 

 kownikoff investigated Pennsylvania petroleum is indeed erroneous,* and 

 a closer study shows that the naphtenes cannot be contained in Pennsyl- 

 vania petroleum in any considerable quantity on account of their higher 

 specific gravity as already shown (page 143): 



* In a private communication, I am informcrl by Professor Markownikoff that 

 lie has not included Pennsylvania petroleum in liis investigations. 



