Rollo's Philosophy Part 17

"It won't go out, unless you put it away down into the vinegar," said Dorothy.

"Yes it will," said Rollo; "we are only going to dip it down a little way, just into the choke damp, and it will go out."

"It won't go out, child," said Dorothy. "There's nothing to put it out."

"Well, you'll see. Won't it go out, Jonas?"

"I don't know," said Jonas.

"Don't know?" said Rollo. "Why, you told me that choke damp would put out a blaze."

"Yes," said Jonas, "I am sure of that; but there are a great many ways of failing in trying experiments."

"Well," said Rollo, "that may be; but this will not fail, I know, for I can see the little bubbles of choke damp coming up. There are millions of them."

By this time Jonas thought that the tumbler was filled with the gas, which was rising from the chalk and vinegar. So he rolled up a piece of paper, and set the end on fire, and, when it was well burning, he plunged the end of it into the tumbler. To Rollo's great disappointment and mortification, it continued to burn about as much as ever. The flame crept rapidly up the paper, and Jonas had soon to run with it across the floor and throw it into the fire, to avoid burning his fingers. Dorothy laughed aloud; Jonas smiled; and as for Rollo, he looked disappointed and vexed, and appeared to be overwhelmed with chagrin.

Dorothy continued to laugh at them, while Jonas went to the pump and washed out the tumbler. At length she said,--

"But come, Rollo, don't be so disconsolate. You look as if you had swallowed all the choke damp."

"Yes, Rollo," said Jonas, "we must keep good-natured, even if our experiments do fail."

"Well," said Rollo, "I mean to ask Miss Mary again, and then we can do it, I know."

Rollo accordingly went, the next day, to ask Miss Mary about the cause of the failure. Miss Mary said that she could not think of any thing which was likely to be the cause, unless it was that they put too large a flame into the tumbler.

"Well," replied Rollo, "and what harm would that do? Won't the choke damp put out a large flame?"

"Yes," replied Miss Mary, "if it only fairly surrounds and covers it; but, then, if you put a large flame into a tumbler, it makes the first instant, a great current of air, and so the choke damp might be blown out, and common air get in, and so keep the paper burning."

"How does it make a current of air?" asked Rollo.

"Why, the heat of the flame, when you first put the paper in," replied Miss Mary, "makes the air that is above it lighter; and the common air all around crowds in under it, in buoying it up; and by that means, if the flame is too large, common air is carried into the tumbler. You ought to make a very small flame, if you leave the top of the tumbler open."

"How can we make a small flame?" said Rollo.

"One good way," replied Miss Mary, "is to roll up some paper into a very small roll. I will show you how."

So Miss Mary took a piece of paper, and cut it into the proper shape with her scissors, and then rolled it up into a long and very slender roll; one end of it was not much larger than a large knitting-needle.

She gave this to Rollo, and told him that, if he tried the experiment again, he must light the small end, and it would make a flame not so big as a pea.

Rollo explained to Jonas what Miss Mary had said, and they resolved on attempting the experiment again that evening. And they did so. Dorothy stood by watching the process, as she had done the evening before, but Rollo did not a.s.sert so confidently and positively what the result would be. He had learned moderation by the experience of the night before.

When all was ready, Jonas lighted the end of the slender roll in the lamp, and plunged it carefully into the tumbler. It went out immediately.

"There!" said Rollo, clapping his hands, "it goes out."

"Why, it is only because the wind blew it out."

"No, Dorothy," said Rollo, "there isn't any wind in the tumbler."

"Yes," replied Dorothy, "when you push it down, it makes a little wind, just enough to blow it out."

"Get another tumbler," said Jonas, "and let us see."

So Dorothy brought another tumbler, and Jonas put the burning end of the paper down into it, with about as rapid a motion as that with which he had put it before into the tumbler he had at first. The paper continued to burn.

"There," said he to Dorothy, "when I put it down into common air, it burns on the same as ever; so it can't be that the wind puts it out."

Jonas repeated the experiment a number of times; the effect was always the same. Whenever he put it into the tumbler of common air, it burned on without any change; but whenever he put it into the choke damp, it immediately went out. Even Dorothy was satisfied that there was a difference in the kind of air contained in the two tumblers.

That evening, when Rollo gave his mother a full account of their attempts,--describing particularly their failure at first, and their subsequent successes,--his mother seemed much interested. When he had finished, she said,--

"Well, Rollo, I don't see but that you have learned two lessons in philosophy."

"Two lessons?" said Rollo.

"Yes," replied his mother. "The first is, that fire will not burn in choke damp; and the second is, that it requires nice attention and care to verify philosophical truths by experiment."

"Yes," said Rollo, "we missed the first time, just because we had too big a paper."

QUESTIONS.

Why did Jonas suppose that the stump would not burn? What was Rollo's first mode of setting it on fire? How did it succeed?

What did Jonas do with his axe, when he came? What was the object of this? What did he say was necessary to make fires burn? What did Rollo at first think was the reason why the bark went out when held over the fire? What did he next think was the reason? How did Jonas say that different kinds of airs were prepared? In what places did he say that choke damp was naturally produced? How did they attempt to prepare some of this gas? Did they succeed in preparing it? Did they succeed in their experiment at first? What was the cause of the failure?

CHAPTER X.

GRAVITATION.

One evening, after tea, when Rollo was a pretty big boy, he came and began to climb up into his father's lap. When he had climbed up, he took his place astride of his father's knee, as if he were riding a horse.

His little brother Nathan came up and stood near, wanting to get up too, only there was not room. His cousin James was there, that evening, on a visit. He sat upon a cricket before the fire, and his mother was at the table doing some sort of work.

"O dear me!" said Rollo's father, imitating the tone in which Rollo sometimes uttered that exclamation.

"What, sir?" said Rollo.

"Why, I should like very well to hold you in my lap," said his father, "if it was not for the great mighty earth, down below us."

"How?" said Rollo. He did not know what his father meant.