116 PROCEEDINGS OF THE AMERICAN ACADEMY. 



distilled between 126°. 8 and 129°. 1, or in the mean at 127°. 6 ; its com- 

 position was based upon a determination of its vapor density, but it was 

 not supported by analysis. The observations of Warren were appar- 

 ently confirmed by similar distillates separated from Ohio and Canadian 

 petroleum.* Distillates collected at 126°-127° from these oils after the 

 eleventh fraction gave values in vapor density determinations correspond- 

 ing to that of octane. But evidently such determinations, unsupported 

 by other data, are less reliable, especially in products not fur removed in 

 boiling points from other isomers. Although our former results appar- 

 ently confirmed the presence of an octane at 12G°-r27°, those values 

 were accepted as provisional, to be supported or modified by more pro- 

 longed distillations which have now been made. 



Under a constant tension of 730 mm., forty-two distillations were 

 made between 121° and 130° through Hempel bead columns. Of the 

 last distillates scarcely any remanied at 126°-127°, or between this 

 point and 130°, and very little at 125°-126°. The greater portion, 

 200 grams, collected at 124°-125°, normal conditions. There is, there- 

 fore, in Ohio petroleum, no octane with a boiling point higher than 125°. 

 After purification with a mixture of nitric and sulphuric acids and 

 sodium, the distillate 124°-125° was shown by analysis to have the 

 composition for octane. 



0.1471 gram of the oil gave 0.4544 gram CO2, and 0.2077 gram H5O. 



Calculated for CgH,,. Found. 



C 84.22 84.26 



H 15.79 15.70 



After thorough treatment with fuming sulphuric acid, this octane gave 

 0.7183 as its specific gravity. Another portion, carefully purified with 

 a mixture of nitric and sulphuric acids gave 0.7134. The specific 

 crravity of the synthetic hydrocarbon was given by Thorpe as 0.7188. 

 The crude distillate, with no purification, gave as its specific gravity 

 0.7243. Its vapor density was found by the method of Hofmaun. 



0.1578 gram of the oil gave 84.4 c.c. of vapor at 182°, and under a 

 tension of 462 mm. 



Calculated for CgHis. Found. 



3.95 3.96 



In the formation of monochloroctane from this distillate, the hydro- 

 carbon was exposed to the action of chlorine in the cold until the 



* Mabery, Proc. Amer. Acad., XXXI. 32, 57. 



