combustion. For instance, here is a lamp which, simple though it be, is
the original, I may say, of a great variety of lamps which are constructed
for divers purposes for light-houses, microscopic illuminations, and
other uses; and if it were proposed to make it burn very brightly, you
would say, If a candle burnt better in oxygen, will not a lamp do the
same? Why, it will do so. Mr. Anderson will give me a tube coming from
our oxygen reservoir, and I am about to apply it to this flame, which I
will previously make burn badly on purpose. There comes the oxygen: what a
combustion that makes! But if I shut it off, what becomes of the lamp? [The
flow of oxygen was stopped, and the lamp relapsed to its former dimness.]
It is wonderful how, by means of oxygen, we get combustion accelerated.
But it does not affect merely the combustion of hydrogen, or carbon, or
the candle; but it exalts all combustions of the common kind. We will take
one which relates to iron, for instance, as you have already seen iron
burn a little in the atmosphere. Here is a jar of oxygen, and this is a
piece of iron wire; but if it were a bar as thick as my wrist, it would
burn the same.
[Illustration: Fig. 23.]
I first attach a little piece of wood to the iron, I then set the wood on
fire and let them both down together into the jar. The wood is now alight,
and there it burns as wood should burn in oxygen; but it will soon
communicate its combustion to the iron. The iron is now burning
brilliantly, and will continue so for a long time. As long as we supply
oxygen, so long can we carry on the combustion of the iron, until the
latter is consumed.
We will now put that on one side, and take some other substance; but we
must limit our experiments, for we have not time to spare for all the
illustrations you would have a right to if we had more time. We will take
a piece of sulphur you know how sulphur burns in the air well, we put it
into the oxygen, and you will see that whatever can burn in air, can burn
with a far greater intensity in oxygen, leading you to think that perhaps
the atmosphere itself owes all its power of combustion to this gas. The
sulphur is now burning very quietly in the oxygen; but you cannot for a
moment mistake the very high and increased action which takes place when
it is so burnt, instead of being burnt merely in common air.
[Illustration: Fig. 24.]
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