petroleum is deposited from the gas. It is, however, safe to assume that
they are the products of one material, the lighter element separating
from the heavier under certain degrees of temperature and pressure.
Thus petroleum may separate from the gas as asphaltum separates from
petroleum. But some speculative minds consider natural gas to be a
product of anthracite coal. The fact that the great supply-field of
natural gas in Western Pennsylvania, New York, West Virginia, and
Eastern Ohio is a bituminous and not an anthracite region does not of
itself confute that theory, as the argument for it is, that the gas may
be tapped at a remote distance from the source of supply; and, whereas
anthracite is not a gas-coal, while bituminous is, we are told to
suppose that the gas which once may have been a component part of the
anthracite was long ago expelled by Nature, and has since been held in
vast reservoirs with slight waste, awaiting the use of man. That is one
theory; and upon that supposition it is suggested that anthracite
may exist below the bituminous beds of the region lying between the
Alleghany Mountains and the Great Lakes. Another theory is, that natural
gas is a product of the sea-weed deposited in the Devonian stratum. But,
leaving modern theories on the origin of natural gas and petroleum, we
may suppose the natural gas jets now burning in the fissures of the
Caucasus to have started up in flames about the time when, according
to the Old Testament, Noah descended from Mount Ararat, or very soon
thereafter. In the language of modern science it would be safe to say
that those flames sprang up when the Caucasus range was raised from
beneath the surface of the universal sea. The believer in biblical
chronology may say that those fires have been burning for four thousand
years--the geologist may say for four millions.

We know that Alexander the Great penetrated to the Caspian; and in
Plutarch we read: "Hence [Arbela] he marched through the province