In the direct distillation of cannel-coal for the production of paraffin, it is necessary that the perpendicular tubes or retorts into which the coal is placed be heated only to a certain temperature, which is considerably lower than that applied when the object is the production of coal-gas.  By this means nearly all the volatile matters pass over in the form of condensible vapours, and the crude oils are at once formed, from whence are obtained at different temperatures various volatile ethers, benzene, and artificial turpentine oil or petroleum spirit.  After these, the well-known safety-burning paraffin oil follows, but it is essential that the previous three volatile products be completely cleared first, since, mixed with air, they form highly dangerous explosives.  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