“Yes,” said Rollo, “they burn, they burn most beautifully. File me some more, Jonas, and let me carry them in and show them to my mother.”
Jonas accordingly filed some more filings, and Rollo went in with them very eagerly, to show to his mother.
“Just look,” said Rollo; and so saying, he held the paper over the lamp in such a manner as to let the filings slide down into the flame just as Jonas had done. The experiment succeeded perfectly well, as it had done before.
“So you see that it will burn,” said Mr. Holiday, “if you heat it hot enough.”
“If you make it small enough, you mean,” said Rollo.
“I suppose the smallness of the particles is of no consequence,” replied his father, “excepting to make it easier to heat them.”
“Why, father,” said Rollo, “I might put the end of a knitting-needle in the lamp, and I don’t see why it wouldn’t become as hot as one of the iron filings.”
“Because,” said his father, “a part of the heat would be conveyed away through the knitting-needle towards your hand, and that would keep the end which was in the flame cooler.”
“Yes,” said his father. “The heat moves off very fast in such a case. You know, if you take a pin between your fingers, and hold the head of it in the lamp, the heat will almost immediately move along the metal, so as to heat the end that you are holding, and burn you.”
“Yes, sir,” said Rollo; “I have got burned so, very often.”
“And of course much more heat would be conveyed away when the metal was as thick as a knitting-needle.”
“Well, father,” said Rollo, “suppose a piece of the knitting-needle was broken off, and made so small that it could all be in the flame; then would it burn?”
“How could you keep it there?” asked his father.
“Why—I don’t know,” said Rollo, hesitating. “Couldn’t we contrive some way to keep it there?”
“Couldn’t we put it on the end of the wick?” asked Rollo.
“Yes,” said his father, “perhaps we might; but then the end of the wick is cool, and that would cool it.”
“O, father,” said Rollo, in a tone of great surprise, “the end of the wick cool, when it is right in the middle of the blaze!”
“I mean,” replied his father, “that it is cool compared with the heat necessary for inflaming the iron. It would feel very hot to your fingers, I have no doubt, for it is filled with boiling oil. But then even the heat of boiling oil is less than that necessary to inflame iron; and so the contact of the wick with such a piece of iron as you propose, would keep it cool, or rather keep it from getting hot enough to take fire.”