172 RESEARCHES ON THE VOLATILE HYDROCARBONS. 
inaccuracy in the determination of the boiling-points, when it is considered that great 
care was taken to obtain a high degree of purity and accuracy, and when it is consid- 
ered also that previous observers have made this discrepancy larger than mine. It 
was On account of the fact that so small a discrepancy would naturally raise a doubt 
as to. the reliability of the determinations, and for the reason that Kopp* has consid- 
ered this series of alkaloids as agreeing tolerably well with his general law, that spe- 
cial eare was taken on my part to arrive at a correct result. I am confident, there- 
fore, that the boiling-point difference here will not be found to vary more than a frac- 
tion from 17°. Of the absolute accuracy of the boiling-points themselves I do not 
speak so confidently, since these depend so much on the accuracy of the thermometer 
at these high temperatures; but the correction of any errors which may have arisen 
from this source would not be likely to alter the relation, and the difference between 
the boiling-points would still remain about the same. This remark applies with equal 
force as to the reliability of the other boiling-points presented in this paper, especially 
of those of high temperatures. 
It remains now to consider the foregoing facts with reference to the other theories 
mentioned. i 
Or tHe CatcuLaTepD Borine-pornts or Hyprocarsons By Scurdpur’s THrory. 
The subjoined tables exhibit the theoretical boiling-points of the above-mentioned 
hydroearbons,t as ealculated according to Schréder’s last theory, in comparison with 
the boiling-points actually found. By this theory, as already stated, each double atom 
of carbon (C,) contained in a body is supposed to influence the boiling-poimt by 30°, 
and each double atom of hydrogen (H,) to influence the same — 10°; from the sum 
of these influences the number 70 is in all cases to be deducted, in order to find the 
boiling-point. 
1. Hydrocarbons from Pennsylvania Petroleum. 
Ist Series. 
—" itp, | vou by Schrader cilia aot Deter 
©sHy 0.0 (?) 0 : 
Cio Bas 30.2 20 BO 
Cs Hye 61.3 40 213 | 
Cu Hig 90.4 60: 80.4 ! 
Ce His 119.5 80° 39.5 | 
Cs Hin 150.8 100 50.8 
* Annalen der Chemie und Pharmacie, 1855, XCVI. 24. 
ft To avoid useless repetition, the hydrocarbons from Albert coal-oil will be omitted in this series of 
tables, they being considered identical with the corresponding bodies from petroleum. 
