148 
THE GEOLOGIST. 
CjQ Hp hydride of amyl, boiHn2;-point 34° C. 
hydride of hexyl, ^„ 68° C. 
His hydride of heptyl, „ 98° C. 
Hig hydride of octyl, „ 119" C. 
In addition to these he obtained a small quantity (about one gramme) of a 
liquid boiling between 20° and 30° C, and hence we may infer that also hy- 
dride of butyl is present in small quantities. 
The author stated in the paper above alluded to that hydride of amyl 
boils at 39° C. The same compound from petroleum boils at 34° C. He 
finds, however, that the presence of traces of foreign substances alter the 
boiling-point of this body very considerably. Thus, for instance, he ob- 
tained from the crude oil about one ounce of a liqiiid which boiled from 
15° to 20° C. ; after treatment with nitric acid, the volume of the liquid re- 
mained almost unchanged, showing that only a very small quantity of sub- 
stance had been removed ; but, after drying with potash and rectifying 
over sodium, it was found that a mere trace of the liquid boiled below 30° 
C ; nearly the whole distilled at 34° C, and consisted of hydride of amyl. 
Of the four hydrides which he isolated, he had only prepared the hy- 
dride of heptyl in quantity ; four gallons of turpentine substitute boiling 
between 80° and 150° C, yielded three pounds of the pure compoimd. 
In order to obtain from this other heptyl compounds, it was transformed 
into the chloride according to the excellent method described by Hugo 
Miiller,* which consists in the addition of a small quantity of iodine to 
the substance which is to be treated with chlorine. The substitution oc- 
curs 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 hy- 
drochloric acid vapours. 
Hence it is seen that the constitution of American petroleum, at least 
that portion boiling below 120° C, is quite analogous to that of the oil 
from cannel tar. 
Petroleum consists mainly of the hydrides of the alcohol radicles, it 
contains very small quantities of benzol and toluol, and probably traces 
of olefines, whilst 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 composition and 
physical characters of the hydrides Cn Iln+2, also benzol and its homo- 
logues and olefines .f 
The rock oils obtained in other countries appear to posses a somewhat 
similar constitution. 
Thus, for instance. Warren de la Kue and Hugo MiillerJ found in the 
Rangoon tar, benzol, toluol, xylol, and cumol and hydrocarbons of the for- 
mula Cn Hm+2. They were, however, unable to isolate from these a com- 
pound of definite composition and boiling-point. The rock oil from Sehnde, 
in Hanover, consists, according to the investigation of Busenius, Eisen- 
stuck,§ and Uellsmann,|| of hydrocarbons of the same general formula, but 
they like\^ ise failed to olDtain definite products. 
Pebal and Freund** found in the rock oil from Gallicia benzol and homo- 
logues, carbolic acid and homologues, and hydrocarbons which are not 
attacked by the strongest acids, and probably identical with those previ- 
ously mentioned. 
* Journ, Chem. Soc., 15, 41. f Phil. Trans. 1857. t Jahresbericht, 9, 606. 
§ Liebig's Aimalen, 113-115. |1 lb. 114-279. ** lb. 115, 119. 
