1903.) MABERY—THE COMPOSITION OF PETROLEUM. 41 
oil. It is interesting to note that Pennsylvania petroleum alone, 
unless we include the analogous Berea Grit and other similar sand- 
stone oils of southern Ohio and Virginia, contains the unbroken 
series up to and including the solid paraffine constituents. 
Although the Ohio Trenton limestone oil and the Canadian 
Corniferous oil contain paraffine, the former in large proportions, 
the liquid members of series C,H.,4. stops with C,H. in both 
Canadian and Ohio oil. The liquid hydrocarbons from there on, so 
far as examined, are members of series poorer in hydrogen. 
The series C,H,, has been variously named. When first discov- 
ered in petroleum, and the hydrocarbons found to be identical with 
the hydrogen addition products of benzol and its homologues, the 
hydrocarbons from petroleum were described as hexahydro-bodies. 
On the discovery of a long series of these hydrocarbons in Russian — 
oil, Markownikow suggested the name naphthenes. But when later 
the origin and nature of the methylenes were better understood and 
cyclic hydrocarbons found in petroleum identical with the 
synthetic products, the name methylene was adopted for the lower 
petroleum hydrocarbons. ‘These closed-chain hydrocarbons differ 
in their deportment toward reagents from those with an open-chain, 
C,H.,4.. While it is to be assumed that the series C,H,, is rep- 
resented in its higher members by the methylenes, some extension 
of the nomenclature is necessary to include those bodies. There 
can evidently be but one ring with these proportions of carbon and 
hydrogen. For instance, the hydrocarbon C,,H,, must be regarded 
as a long chain with the ends connected, dodecamethylene, or a 
lower ring with several side chains. 
When the series C,H,,_, is reached it becomes necessary to 
assume a union of two rings attached by one carbon atom in each 
ring. In the series C,H,,_, the union would be between two 
carbon atoms in each ring and the members should include, for 
instance, octohydronaphthaline which would represent the hydrocar- 
bon C,,H,,. In the line.of this suggestion, following the analogy of 
naphthaline, one side chain should be capable of oxidation giving 
a derivative of phthalic acid. But the methylene hydrocarbons 
seem to possess a different order of stability toward the action of 
reagents, and we have observed this peculiarity in bodies separated 
from petroleum which appear to be derivatives of the methylenes. 
For instance, the nitrogen compounds separated from California 
crude oil cannot be oxidized into closely allied products, the 
