60 PROCEEDINGS OP THE AMERICAN ACADEMY 



publication of my first memoir, above referred to, tbis chemist 

 appears to bave made a special search for these bodies, which were 

 entirely overlooked in his earlier research, and such of them 

 as he found he seems to have obtained in small proportion, — quite 

 the reverse of my experience. E. g., of the body boiling at 61°. 3, 

 which, as stated, he did not find, the proportion of my product, as 

 compared with that boiling at about 68°, was as 7 to 8. 



In the earlier stage of the distillation, in the manufacture of 

 "illuminating oil" or " refined petroleum, " (a medium product, 

 amounting to some 70 per cent of the crude material,) there is ob- 

 tained, as is well known, a considerable quantity — frequently 

 about 15 per cent — of a colorless and highly volatile liquid, vari- 

 ously known in commerce as naphtha, spirits of petroleum, and, 

 improperly, as benzine. Although containing some of the sub- 

 stances that more especially characterize the heavier or medium 

 portion of the petroleum, the larger proportion of this naphtha is 

 composed of bodies whose boiling-points range from 0° to 150°, 

 these being the limits of my provisional 1st and 2d series, and is 

 therefore a convenient source from which these for the most part 

 may be obtained. Some manufacturers separate this naphtha, ei- 

 ther by a second distillation or during the distillation of the crude 

 petroleum, into two parts, a "light" and a "heavy naphtha." 

 The former of these is the product commercially known in the 

 United States as "Gasolene," which is more or less extensively 

 employed, mixed as vapor with atmospheric air, as a substitute 

 for coal gas. It was from this "gasolene" or " light naphtha, " 

 having the specific gravity 0.65 at 15° C, that the hydrocarbons 

 comprised in my 1st and 2d series were chiefly procured. Although 

 this product contains a larger proportion of some of the lower or 

 medium members of these two series, — as its low specific gravity 

 and high degree of volatility would indicate, — it also contains 

 considerable quantities of the higher ones; but the latter may be 

 obtained in greater abundance from the "heavy naphtha," and 

 in notable quantity also from the medium product described as 

 " illuminating oil, " from which to a considerable extent it may 

 be conveniently procured while operating to obtain the members of 

 the 3d series, of which this product is chiefly composed. 



In the manufacture of these naphthas, a large portion of the two 

 most volatile constituents of the petroleum — those boiling at 0° 

 and 8° respectively — is generally allowed to escape condensation, 

 and to a considerable extent, also, the two next higher ones, boil- 



