ives. To the fact
that the operation is carried on in the manufactories with great care and
accuracy can only be attributed the comparative rareness of explosions of
the oil used in households.

After paraffin, the heavy lubricating oils are next given off, still
increasing the temperature, and, the residue being in turn subjected to a
very low temperature, the white solid substance known as paraffin, so
much used for making candles, is the result. By a different treatment of
the same residue is produced that wonderful salve for tender skins, cuts,
and burns, known popularly as _vaseline_. Probably no such
widely-advertised remedial substance has so deserved its success as this
universally-used waste product of petroleum.

We have noticed the fact that in order to procure safety-burning oils, it
is absolutely necessary that the more volatile portions be completely
distilled over first. By Act of Parliament a test is applied to all oils
which are intended for purposes of illumination, and the test used
consists of what is known as the flashing-point. Many of the more
volatile ethers, which are highly inflammable, are given off even at
ordinary temperatures, and the application of a light to the oil will
cause the volatile portion to "flash," as it is called. A safety-burning
oil, according to the Act, must not flash under 100 deg. Fahrenheit open
test, and all those portions which flash at a less temperature must be
volatilised off before the residue can be deemed a safe oil. It seems
probable that the flashing-point will sooner or later be raised.

One instance may be cited to show how necessary it is that the native
mineral oils which have been discovered should have this effectual test
applied to them.

When the oil-wells were first discovered in America, the oil was obtained
simply by a process of boring, and the fountain of oil which was bored
into at times was so prolific, that it rushed out with a force which
carried all obstacles before it, and defied all control. In one instance
a column of oil shot into the air to a height of forty feet, and defied
all attempts to keep it under. In order to prevent further accident, all
lights in the immediate neighbourhood were extinguished, the nearest
remaining being at a distance of four hundred feet. But in this crude
naphtha there was, as usual, a quantity of volatile spirit which was
being given off even at the temperature of the surrounding atmosphere.
This soon bec