Petrolatum

3694

Petroleum

to one of the distillates of petroleum; prac-
tically the same as gasoline. See PETROLEUM.
Petrolatum, or Petroleum Jelly, an am-
ber-colored, translucent, jelly-like substance,
which is obtained by distilling off the more
volatile portions of petroleum, and purify-
ing the residue by filtration. It is largely
used as a lubricant, as a protection for pol-
ished iron and metals, and in pharmacy as
an unguent and a base for ointments. It is
sometimes known as Vaseline, though this
term is a trade-mark.

Among the first historic records of petro-
leum is that of its use on the walls of Baby-
lon and Nineveh about 2,000 B.C., and for
ages seepages of crude oil have been drawn
on and used by the people of Egypt, Meso-
potamia, India, and China. For many cen-
turies hand-dug wells and pits were used for
the collection of petroleum, while the modern
method of cable tool drilling, now commonly
used in oil fields, is believed to have originated
with the Chinese centuries ago. But the mod-
ern industry really began when the Drake

Nevski Prospect, Leningrad.

Petroleum, a liquid consisting of many
hydrocarbons dissolved in each other, whose
aggregate composition varies greatly. It is
probably produced in part by the slow de-
composition of both animal and vegetable
matter, deeply buried in sedimentary rocks;
and in part by the fermentation and decay
of organic matter at the earth's surface, the
resulting oil being deposited contemporan-
eously with the rocks in which it is preserved.
Petroleum is present, in at least minute quan-
tities, in nearly all of the unaltered sedi-
mentary rocks from Lower Silurian to Recent
in age. The commercially important deposits
occur as concentrations in porous reservoir
rocks, such as sandstone or limestone, sealed
by overlying less pervious strata.

well was drilled near Titusville, Pa., in Aug-
ust, 1859. Besides the United States, Rou-
mania, Canada, Russia, and Galicia became
important producers at an early date, and
the later important additions to the list in-
clude Mexico, Persia and Venezuela. The in-
dustry is now practically world wide.

Approximately two-thirds of the world's
current supply of oil is obtained from the
United States. Russia ranks next in impor-
tance and Venezuela third. In the United
States, Texas leads in output, followed by
Oklahoma and California.

Two general methods of drilling are in
common use in the United States, the stand-
ard or cable-tool method and the rotary
method. Rotary tools have the advantage