454 
MR. C. SCHORLBMMER 0N [THE NORMAL PARAFFINS. 
than the corresponding compounds from petroleum, and also the barium salts of the 
two caproic acids exhibit a decided difference. The hexane from petroleum is certainly 
not a pure compound; but whether this is the cause of the difference between the two 
hydrocarbons, or whether we have here a case of fine isomerism for which an explana¬ 
tion has to be found, it is at present impossible to decide.”'" 
I believe the results of my present research speak strongly in favour of the latter 
view. Further experiments are, however, required to elucidate these points, as well 
as the constitution of the olefines from petroleum which combine readily with hydro¬ 
chloric acid in the cold. 
Another point which wants clearing up is the fact that the normal paraffins from 
petroleum have a higher specific gravity than those obtained from any other source. 
This is probably due to some admixture, for I found that on treating hexane with hot 
nitric acidt the specific gravity of the noil-oxidised portion decreased and became at 
last constant, being 0’6 63 at 17°, or the same as that of hexane from mannite and of 
normal dipropyl.| The normal paraffins from petroleum appear, therefore, not to be 
pure compounds; and for several reasons I am inclined to belive that petroleum, after 
being freed from olefines, aromatic hydrocarbons, and those of other series, consists of 
an inextricable mixture of isomeric and homologous paraffins, in which, however, 
the normal hydrocarbons preponderate. This would certainly explain why it is so 
extremely difficult to isolate from it bodies having a constant boiling point,§ but not 
why the normal hexylene obtained from petroleum will not unite with hydrochloric 
acid under the same conditions as that prepared from mannite. 
A continuation of these researches has been already commenced. My friend 
Thorpe, who made the most interesting discovery that the terebinthinate exudation 
of Pinas Sabiniana contains a large quantity of normal heptane, || has kindly invited 
me to join him in the chemical investigation of this hydrocarbon. At the same time 
we shall compare it with other “ normal ” heptanes from different sources. 
* Pliil. Trans., Yol. 162, p. 119. 
f Proc. Roy. Soc., vol. xvi., p. 372. 
+ Phil. Trans., Yol. 162, p. 120. 
§ Journ. Ohem. Soc., 1875, p. 306. 
|| Journ. Chem. Soc., 1879, p. 296. 
