requires a high temperature for combustion, it is closely related to
other products of coal oil, such as naphtha and gasoline, which become
inflammable at a low heat and are therefore very dangerous. Since the
cheap grades of kerosene approach these products in quality, care should
be taken to see that it is of high "proof" in order to prevent
explosions. The proof required of kerosene differs in various States;
that in some is as low as 100 degrees Fahrenheit, that is, the
temperature at which the oil will give off vapors that will ignite.
This is too low a proof, for such a degree of temperature is quite common
in the household. It is safe only to use that kerosene which is at least
140 degrees proof, for then, even though the oil is spilled, there is
little danger that it will ignite except in the immediate presence of
flame. There is no danger at all in soaking wood with this kind of oil
in a stove or grate wherein the fire has gone out.

To test kerosene, put a thermometer into a cup partially filled with
cold water, and add boiling water until the mercury stands at 130
degrees Fahrenheit. Then take out the thermometer and pour two
teaspoonfuls of kerosene into the cup and pass over it the flame of
a candle. If the oil ignites, it is unsafe.

In order to prevent the flame from running down into the lamp and
causing an explosion, the wick should be soft, filling the burner
completely. The highest efficiency in the form of illumination is
obtained by round burners, especially those in lamps which admit air
to the inside of the wick and so induce the largest possible amount
of combustion. Such a lamp produces quite a high degree of heat, and
will answer the purpose of an oil-stove in a small room.

Contrary to the popular idea, wicks should be carefully trimmed with