The reason why : $b a careful collection of many hundreds of reasons for things which, though generally believed, are imperfectly understood. A book of condensed scientific knowledge for the million — John Stuart Mill — John Shaqi
The reason why : $b a careful collection of many hundreds of reasons for things which, though generally believed, are imperfectly understood. A book of condensed scientific knowledge for the million
John Stuart Mill · en
297. _Why does wood, when ignited, burn longer than paper?_
Because, being a denser substance, it submits a _larger number of
particles_, within a given space, to the action of the heat, and the
formation of gases.
298. _Why do we, in lighting a fire, first lay in paper, then wood, and
lastly coals?_
Because the paper is more easily ignited than wood, and wood than
coals; therefore the _paper_ assists the ignition of the _wood_, and
the _wood_ assists the ignition of the _coals_.
[Verse: "It is a good thing to give thanks unto the Lord, and to
sing praises unto thy name, O Most High."--PSALM XCII.]
299. _Why will not wood ignite by the flame of a match?_
It will do so, unless there is a great disproportion between the size
of the wood and the flame of a match. A _thin_ piece of wood will
ignite, but a square block will not, because the heat of the flame is
insufficient to raise the temperature of a _large surface_ to the point
that will drive out its gases.
300. _Why do we place the paper under the wood, and the wood under the
coals?_
Because heat and flame, when surrounded by air, have a strong tendency
to spread themselves _upwards_.
301. _Would it be possible to light the coals by putting the paper and
the wood upon the top?_
It would be possible; but the loss of heat would be so great, that a
_much larger quantity_ of paper and wood would be required.
302. _Why does a poker laid across the top of a dull fire revive it?_
Because the poker _radiates_ the heat it receives from the fire
downward upon the fuel.
Because, also, it divides the ascending air, and thereby _creates
currents_.
The amount of good which the poker does to the fire is very slight
indeed. Generally, the housewife stirs the fire first, and blows
or brushes away the ashes that prevent the influx of air. She then
places the poker upon the top, and the popular mind supposes that
the poker "draws" the fire. The custom of placing a poker over
the fire is of very remote antiquity. It was once believed that
forming _a cross_, by placing the poker over the bars, protected
the fire from the hostility of malignant _witches_!
303. _Why should fire-places be fixed as low as possible in rooms?_
Because heat _ascends_, and when the fire-places are high the lower
parts of the room are _inadequately warmed_.
Also, as currents of air fly towards the fire, elevated fire-places
_cause drafts_ about the persons of the inmates to a much greater
extent than they would if they were lower down.
[Verse: "Unto thee, O God, do we give thanks: for that thy name is
near thy wondrous works declare."--PSALM LXXV.]
304. _Why, if a piece of paper be laid with its flat surface upon the
fire, will it "char," but not ignite?_
Because, as in the case of the proper candle-extinguisher, the
_carbonic acid gas_ accumulating beneath it prevents its igniting.
305. _Why, if you direct a current of air towards the paper, will it
burst into a blaze?_