112 PROCEEDINGS OF THE AMERICAN ACADEMY. 



concordant. Pelouze and Cahours first announced in their series of 

 hydrocarbons an octane, boiling point 116°-118°, and a little later 

 Schorlemmer* found a body in coal tar distilling at 119°-122°, and an- 

 other at 124°, both with the composition required for octane. Possibly 

 led to believe by the results of Beilstein and Kurbatoff that the distillate 

 119°.5-122° is hexahydroisoxylol, in liis later summation of the octanes 

 known Schorlemmer seems to repudiate the one boiling at 119°-122°, 

 which he had previously described. Warren recognized two octanes, one 

 boiling at 119°. 5, and another boiling at 127°. 6. These bodies were 

 identified alone by vapor density determinations and boiling points ; no 

 analyses were given. In the separation of the hydrocarbons resulting 

 from the distillation under pressure of menhaden oil, Engler discovered 

 the octane, diisobutyl, boiling point 109°. In support of the work of 

 Pelouze and Cahours, Lemoine f submitted American ligroine to 

 four fractional distillations, collecting distillates within limits of jive 

 degrees, and separated an octane, boiling point 121° at 779 mm. In 

 our experience, the hydrocarbons in petroleum with boiling points not 

 far removed can only be separated by the use of the best possible means 

 for fractional separation, in a long course of distillations. The separation 

 of the octanes, for example, requires a refinery distillate boiling between 

 120° and 170°, and it is not until the twentieth distillation that the 

 octanes begin to accumulate with any degree of purity. In all our ex- 

 periments after the fifth distillation, the octanes are still contained for 

 the most part in the portions above 125°, and they are separated very 

 slowly into their respective fractions. In undertaking further study of 

 the octanes in Ohio petroleum, we procured from the refinery of Messrs. 

 Schofield, Shirmer, and Teagle 72 litres of a burning oil distillate that 

 distilled in our hands, within the limits of ten degrees, in the following 

 proportions : — 



—75° 75°-100° lOO^-llO" 110°-120° 120=-130° 130=-140° 140°-150° 150°-160° +160° 



Litres 10 12 10 8 8 8 5 5 5 



The sulphur compounds were precipitated from these fractions by means 

 of alcoholic mercuric chloride, the oils washed and dried, and the distilla- 

 tion continued within limits of 5°, 2°, and finally within 1°, under a 

 constant tension of 730 mm. In further explanation of what was said 

 above concerning the slow separation of these constituents, the following 

 record of the tenth distillation is given ; when it is borne in mind that 



* Jour. Chem. Soc, XV. 419. t Bull. Soc. Chem., XLI. 161. 



