126 PROCEEDINGS OF THE AMERICAN ACADEMY. 



As will be shown later, the specific gravity assigned by Warren to 

 these constituents is very materially diminished by the removal of the 

 aromatic hydrocarbons, and perhaps of other heavier bodies, that can only 

 be separated by the application of more vigorous means of purification 

 than Warren applied. 



Decane, C10H22, 163°-164°. 



When Pelouze and Cahours announced C^qH^^ as a constituent of 

 Pennsylvania petroleum boiling at 160° ("sensiblement"), the presence 

 in petroleum of the aromatic hydrocarbons had not been demonstrated, 

 and since treatment with concentrated sulphuric acid and carbonate of 

 soda was the sole means of purification, it is evident that their product 

 must have still contained mesitylene, boiling ])oint 163°, which, accord- 

 ing to Engler, is contained in petroleum to the extent of 0.2 per cent. 

 Then the specific gravity, 0.757 at 15°, assigned by them, is somewhat 

 higher than that of this decane with mesitylene entirely removed. War- 

 ren did not observe the collection at this point of a distillate in any con- 

 siderable quantity. But if, as it seems probable, Pelouze and Cahours 

 investigated, not Pennsylvania, but Canadian petroleum, the close agree- 

 ment between their specific gravity of decane at 160° with ours in 

 Canadian petroleum is explained. In attempting to ascertain whether a 

 hydrocarbon with this boiling point is present in Pennsylvania petroleum 

 in any considerable amount, the distillates 150°-170° were carried 

 through a long series of distillations, until several hundred grams col- 

 lected between 158° and 162° under 730 mm., and finally more than 

 100 grams between 162° and 163° under 760mm. One portion of this 

 distillate was dried over sodium for analysis. 



0.1453 gram of the oil gave 0.4560 gram CO2, and 0.1865 gram HjO. 



A determination of the specific gravity of this oil at 20° gave 0.7684. 

 Its vapor density was determined by the Hofmann method in the vapor 

 of aniline. 



I. 0.1327 gram of the oil gave 66.8 c.c. of vapor at 182°, under a 

 tension of 373.2 ram. 

 II. 0.1113 gram of the oil gave 59.5 c.c. of vapor at 182°, under a 

 tension of 354.7 mm. 



