n of the
petroleum and the age of the strata in which it is found. It is almost
certain that in the most recent alluvial formations no oil is ever
found, its latest appearance being in the rocks of the tertiary
period, the place where the solid paraffin is almost exclusively met
with; thus helping to show that the latter has been formed from the
decomposition of the oil, and is not a residue remaining after the oil
has been distilled off. To this conclusion the fact also strongly
points, that the paraffin is much simpler in constitution, purer, and
often of far lighter color than the crude oil, which could not be the
case if it were the original substance.

On examining by the aid of a map the position of the chief oil-bearing
localities it will be noticed that the most prolific spots follow
fairly accurately the contour lines of the country, so that at one
time they formed in all probability a coast line whereon would be
concentrated for climatic reasons most of the animal life both of the
land and sea. During succeeding generations their dead bodies would
accumulate in enormous quantities and be buried in the slowly
depositing sand and mud, till, owing to the gradual alterations of
level, the sea no longer reached the same point. This theory is borne
out by the fact that oil deposits are usually found in marine
sediments, sea fossils being frequently met with. The first process of
the decomposition of the animal remains would consist in the formation
of ammonia and nitrogenous bases, the action being aided by the
presence of air, moisture, and micro-organisms, at the same time,
owing to the well known antiseptic properties of salt, the
decomposition would go on slowly, allowing time for more sand and
inorganic matter to be deposited. In this way the decomposing matter
would be gradually protected from the action of the air, and finally
the various fatty substances would be found mixed with large amounts
of salt, under considerable pressure, and at a somewhat high
temperature. From this adipocere, fatty acids would be gradually
formed, the glycerol being washed away, and finally the acids would be
decomposed by the pressure into hydrocarbons and free carbonic acid
gas. That many of these hydrocarbons would be solid at ordinary
temperatures, forming the so-called mineral wax, which exists in many
places in large quantities, is much easier to imagine, in the light of
modern chemical knowledge, than that the fatty acids