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
245. _Why will a piece of paper held about an inch below the flame of a
candle scarcely become warmed?_
Because the heat _ascends_; and only a little of it falls upon the
paper, and that by _radiation_.
[Illustration: Fig. 2.--DIAGRAM SHOWING THE COMBUSTION OF A CANDLE.]
246. _Why does the lower part of the flame of a candle_ (D) _burn of a
blue colour?_
Because the _hydrogen_ of the tallow, having a stronger affinity for
the _oxygen_ of the air than _carbon_ has, ignites first. Pure hydrogen
burns with a bluish flame.
247. _Why does the middle of the flame_ (C) _look dark?_
Because it is occupied with gaseous vapours, derived from the tallow,
which have not yet _ignited_.
248. _Why does the upper part of the flame_ (B) _produce a bright
yellow light?_
Because it is in this part of the flame that the _hydrogen_ of
the candle, and the _oxygen_ of the air, combine, and there is
just sufficient _carbon_ mixed with the _hydrogen_ to improve its
_illuminating power_.
249. _Why is there a fringe of pale light_ (A) _around the upper part
of the flame?_
Because some of the _carbon_ escapes in a state of _incandesence_, and
as soon as it reaches the air it combines with _oxygen_, and so forms
_carbonic acid gas_.
If any dark body, such as the blade of a knife, be held between
the eye and the flame of the candle, so as to shut off the light
of the more luminous part, the pale fringe around the flame will
be found distinctly perceptible. _Incandesence_ means _heated to
whiteness_.
[Verse: "How oft is the candle of the wicked put out? and how oft
cometh their destruction upon them?"--JOB XXI.]
250. _Why does the flame terminate in a point?_
Because cold air rushes towards the flame in every direction, and
is carried upward. At the point where the flame terminates the cold
currents have so _reduced the temperature_ that combustion can no
longer be sustained.
251. _Why, if you hold anything immediately over the flame, will the
flame lengthen?_
Because, by preventing the rapid escape of the heated air, you maintain
a temperature which _increases the combustion_ at the point of the
flame.
252. _Why should persons whose clothes take fire, throw themselves
down?_
Because flame spreads most rapidly in an _upward_ direction.
253. _Why should persons whose clothes are on fire roll slowly about
when they are down?_
Because they thereby _press out_ the fire.
254. _Why does pressing a flame or a spark put it out?_
Because it prevents the contact of the flame or spark with the _oxygen_
of the air.
Extinguishers put out the flame of candles in the same manner. A
person dies from "suffocation" through the absence of oxygen; and
it is literally practicable to _"suffocate" a fire_.
255. _Why does the wick turn black as it burns?_
Because it consists principally of _carbon_.
256. _Why, when the point of the wick turns out and meets the air, does
it exhibit a bright spark?_