84 
after treatment with nitric acid, the volume of the liquid 
remained almost unchanged, showing that only a very small 
quantity of substance had been removed ; but, after drying 
with potash and rectifying over sodium, it Avas found that a 
mere trace of the liquid boiled heloAv 30° C ; nearly the 
Avhole distilled at 34° C, and consisted of hydride of amyl. 
Of the four hydrides which I isolated, I have only prepared 
the hydride of heptyl in quantity ; four gallons of turpentine 
substitute boiling between 80°— 150° C, yielded three pounds 
of the pure compound. 
In order to obtain from this other heptyl compounds, it 
Avas transformed into the chloride according to the excellent 
method described by Hugo Muller, * which cousists in the 
addition of a small quantity of iodine to the substance which 
is to be treated with chlorine. The substitution occurs much 
more rapidly in this case than when chlorine alone is 
employed, and goes on in absence of the daylight, so that a 
rapid current of chlorine gas can be led into the liquid without 
any chlorine escaping with the hydrochloric acid vapours. 
Hence it is seen that the constitution of American petro- 
leum, at least that portion boiling beloAv 120° C, is quite 
analogous to that of the oil from cannel tar. 
Petroleum consists mainly of the hydrides of the alkoliol 
radicles, it contains very small quantities of benzol and 
toluol, and probably traces of olefines, Avhilst in the cannel 
coal oil the hydrides are found in smaller quantities, and 
benzol and toluol in proportionally larger amounts. In the 
oil obtained by distillation of boghead coal, Greville Williams 
has discovered a series of hydrocarbons possessing the com- 
position and physical characters of the hydrides C„ H n + 2 , 
also benzol and its homologucs and olefiues.f 
The rock oils obtained in other countries appear to possess 
a somewhat similar constitution. 
# Joum. Chem. Soc., 15, 41. 
t Phil. Trans., 1857. 
