behind. Burning phosphorus in confined air will also
take all the oxygen from it, and there are other ways of doing the
same thing. The portion of the air left behind is called nitrogen. You
wouldn't know it from common air by the look; it has no color, taste,
nor smell, and it won't burn. But things won't burn in it, either;
and anything on fire put into it goes out directly. It isn't fit to
breathe, and a mouse, or any animal, shut up in it, dies. It isn't
poisonous, though; creatures only die in it for want of oxygen. We
breathe it with oxygen, and then it does no harm, but good: for if
we breathed pure oxygen, we should breathe away so violently, that
we should soon breathe our life out. In the same way, if the air were
nothing but oxygen, a candle would not last above a minute.

"What a tallow-chandler's bill we should have!" remarked Mrs.
Wilkinson.

"'If a house were on fire in oxygen,' as Professor Faraday said,
'every iron bar, or rafter, or pillar, every nail and iron tool,
and the fire-place itself; all the zinc and copper roofs, and leaden
coverings, and gutters, and pipes, would consume and burn, increasing
the combustion.'"

"That would be, indeed, burning 'like a house on fire,'" observed Mr.
Bagges.

"'Think,'" said Harry, continuing his quotation, "'of the Houses
of Parliament, or a steam-engine manufactory. Think of an iron
proof-chest no proof against oxygen. Think of a locomotive and its
train,--every engine, every carriage, and even every rail would be set
on fire and burnt up.' So now, uncle, I think you see what the use of
nitrogen is, and especially how it prevents a candle from burning out
too fast."

"Eh?" said Mr. Bagges. "Well, I will say I do think we are under
considerable obligations to nitrogen."

"I have explained to you, uncle," pursued Harry, "how a candle, in
burning, turns into water. But it turns into something else. besides
that. There is a stream of hot air going up from it that won't
condense into dew; some of that is the nitrogen of the air which the
candle has taken all the oxygen from. But there is more in it than
nitrogen. Hold a long glass tube over a candle, so that the stream
of hot air from it may go up through the tube. Hold a jar over the
end of the tube to collect some of the stream of hot air. Put some
lime-water, which looks quite clear, into the jar; stop the jar,
and shake it up. The lime-water, which was quite clear before, turns
milky. Then there is some