226 C. M. Warren on the Volatile Hydrocarbons. 
ted by the thermometer in the liquid, is also only apparent, and 
is due to the gradual uncovering of the bulb as the liquid was 
distilled off. At the close of the experiment only about one- 
fifth of the bulb, which unfortunately was a long one, was under 
the surface of the liquid. That this is the true explanation is 
evinced by the fact that during the experiment not a drop of 
liquid was observed to fall back into the retort from the “ eleva- 
for the addition of C,H, in homologous series." The data for 
tabular form, exhibiting at once, in serial order, the formule, 
boiling-points, elementary difference, and the corresponding dif 
1. Of the Hydrocarbons obtained from Pennsylvania Petroleum. 
Ist Series. 
ifference of | Range of Temperature 
Formula. Boiling-point. aman boing point : wits bw eng? 
oc ° 
C; ee 0-0 (?) 
C1982 30°2 O.u- 30-2 15 
Ci2Hy, 61:3 C,H, 81-1 0-8 
C,,H,, 90-4 2 ee eH 29-1 1:0 
C,,H,, 119-5 CHG 291 1:0 
C,,H,, 150°8 CH. 31°3 0-8 
150°8-——5—=30°°16 aah 
Average increment of boiling-point for the addition of C,H,=30 16.) 
BENS EP 0s ie apres adele! sd te C,H, =s0"lh 
In considering this question I shall include the boiling-points of the substances 
which I have separated from Pennsylvania petroleum, cat ile ail distilled ho 
reserving for bsequent memoir all other facts which have 
bodies, 
given in this and in the cia 
1 
“he 
in the determinations of the boi 
th 
