282 PROCEEDINGS OF THE AMERICAN ACADEMY. 



Pentad i'.kanai'htknk, C^H^o. 



From each of the California oils, distillates in vacuo collected at 

 160°— 162 . 50 mm., corresponding nearly to 260°— 262°, atmospheric 

 pressure. The specific gravity of the fraction from Scott's Hill oil was 

 0.8600, and after purification with fuming sulphuric acid, 0.8171. A 

 combustion gave the following values for carbon and hydrogen : — 



0.1454 grm. of the oil gave 0.4558 grm. C0 2 and 0.1829 grm. ILO. 



Calculated for C^IIm. Found. 



C 85.70 85.47 



II 1 1.30 13.97 



The percentages of carbon and hydrogen in the analysis of the two 

 hydrocarbons last described indicate a falling off in the proportions of 

 hydrogen. The deficiency in the analysis is more probably due to loss 

 of carbonic dioxide than of water. Similar variations have been noted in 

 connection with some of the lower hydrocarbons in other crude California 

 oils. The deficiency in hydrogen may indicate, as mentioned heretofore, 

 the presence of hydrocarbons composed with more than one methylene 

 ring, which would require prolonged distillation for their complete 

 removal. From the heavier California oils composed, it appears, largely 

 of asphaltic hydrocarbons, the falling off in the proportion of hydrogen 

 and consequent increase in carbon indicates the presence of hydrocarbons 

 with the formula C n II 2 „_ 2 . Such differences do not appear in determina- 

 tions of molecular weights, but are shown by analysis. 



There are wide variations in the specific gravity of the distillates of 

 California oil above 230° from different sources. This may indicate a 

 certain proportion of hydrocarbons of a lower series than C„II ... and the 

 higher percentages of carbon and lower percentages of hydrogen in some 

 of these oils indicate the possibility of hydrocarbons Cjr,„_ 2 . 



For faithful assistance in this work the following gentlemen should 

 reci lil : Messrs. Shaw. Ames. Richards, Cushing. 



From this examination of California petroleum, the following conclu- 



18 may be drawn : — 



An essential characteristic is the relatively small proportions of the 

 distillates below 225 . The main body of the crude oils from the prin- 

 cipal fields distilling below 225 is composed of methylenes which resem- 

 ble those identified in Russian oil, in boiling points and in specific gra\ ity, 

 ■ I » r andekanaphtene, ( M II .. dodekanaphtene, C II.,. and trideka- 

 naphtene, C l:j II 20 , which differ in boiling points. The proportion of the 



