RESEARCHES ON THE VOLATILE HYDROCARBONS. 143 
tion of any constituent which might be present in small proportion. The process of 
fractioning was continued on this large scale until the separations had so far pro- 
gressed, that at certain temperatures a full barrel of distillate would come off from 
the ten-barrel still employed, without a variation of more than one or two degrees of 
the thermometer. Finally a sample gallon was taken from each of the barrels com- 
posing the last series of products, and these samples were set aside for this investiga- 
tion, which was afterwards conducted in the laboratory. 
Of the Results of Fractional Condensation.— Such of the samples above mentioned as 
promised to yield the different constituents of the naphtha in the largest proportion, 
were subjected to repeated series of fractionings by my process of “ Fractional Con- 
densation.”* As full details of this process have already been given in the memoir 
referred to, it will be needless to repeat them here. It will suffice to say that the 
fractioning in this case was conducted in all respects as there described, and continued 
until the whole of the naphtha taken, boiling between 80° and 170°, had accumulated 
at the four points already indicated, viz. at 80°, 110°,,140°, and 170°; or so nearly the 
whole that the intermediate quantities had become too small to admit of being 
further operated upon. Having therefore so thoroughly exhausted the intermediate 
fractions, I can have no hesitation in asserting that no other body than those alluded 
to was present in the naphtha, — at least, in appreciable quantity, — hence, that the 
parabenzole of Church’ was probably only a mixture of benzole and toluole. I may 
here remark that each of the sample-gallons employed, when subjected to my process 
of fractioning, was found to contain, in variable proportion, all of the constituents of 
the naphtha. 
Of some of the Properties of the Bodies obtained by Fractioning. 
1. Benzoxz. 
* Specific gravity, 0.8957 at 0°, and 0.882 at 15.5. 
Determination of Boiting-pont.— This experiment was conducted in a tubulated retort, 
operating on 150-—200¢.c. of the benzole, containing some pieces of sodium. The ben- 
zole employed had previously been repeatedly boiled with sodium, until the latter 
* Memoirs of the American Academy, 1864. 
f It would appear that the specific gravities of liquids are usually determined at the temperature of the air. 
The result of this is that the determinations made by different observers are not comparable with one another. 
That these specific gravities are not uniformly taken at 0° C.— the temperature which, on account of greater 
convenience, etc. is generally acknowledged to be preferable —is probably due to the fact that the more 
