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
[Verse: "And there are diversities of operations, but it is the
same God which worketh in all."--CORINTHIANS XII.] 92. _Have plants
sometimes a temperature lower than that of the surrounding air?_
Yes. It has not only been found that under particular circumstances
the heat of certain parts of plants is elevated to a very remarkable
degree, but that, under nearly all circumstances, they have a
temperature different from that of the external air, being _warmer in
winter, and cooler in summer_.
CHAPTER VI.
93. _How many kinds of combustion are there?_
There are _three_, viz., slow oxydation, _when little or no light is
evolved_; a more rapid combination, _when the heat is so great as to
become luminous_; and a still more energetic action, _when it bursts
into flame_.
94. _Why does phosphorous look luminous?_
Because it is undergoing slow _combustion_.
95. _Why do decayed wood, and putrifying fish, look luminous?_
Because they are undergoing slow _combustion_. In these cases the heat
and light evolved are at no one time very considerable. But the _total
amount of heat_, and probably of _light_, generated through the lengthy
period of this slow oxydation, _amounts to exactly the same as would be
evolved during the most rapid combustion of the same substances_.
96. _What is flame?_
It is gaseous matter burning at a _very high temperature_.
97. _Why, when we put fresh coals upon a fire, do we hear the gas
escaping from the coals without taking fire?_
Because, the fire being slow, the temperature is not high enough to
ignite the gas.
[Verse: "I will praise thee, O Lord, with my whole heart; I will
show forth thy marvellous work."--PSALM IX.]
98. _What is the gas which escapes from the coals?_
Carburetted hydrogen.
99. _Why, if we light a piece of paper, and lay it where the gas is
escaping from the coals, will it burst into flame?_
Because the lighted paper gives a _heat sufficient_ to ignite the gas;
and because also hydrogen requires the contact of _flame_ to ignite it.
100. _Why, when the coals have become heated, will the hydrogen burst
into flame?_
Because the _carbon_ of the coals, and the _oxygen_ of the air, have
begun to combine, and have greatly increased the _heat_, and have
produced a rapid combustion, _so nearly allied to flame_, that it
_ignites the hydrogen_.
101. _What temperature is required to produce flame?_
That depends upon the nature of the combustible you desire to burn.
Finely divided phosphorous and phosphorated hydrogen will take fire at
a temperature of 60 deg. or 70 deg.; solid phosphorous at 140 deg.;
sulphur at 500 deg.; hydrogen and carbonic oxide at 1,000 deg. (red
heat); coal gas, ether, turpentine, alcohol, tallow, and wood, at
about 2,000 deg. (incipient white heat). When once inflamed they will
_continue to burn_, and will maintain a very high temperature.
102. _What is smoke?_