Rollo went with James to the door of the house where James lived, and then, bidding him good night, he left him, and began to return. When he had got about half way home, he saw a lady and a gentleman coming along the road. As he approached nearer to them, he found that it was his father and mother, taking a walk. Rollo joined them. They said, however, that they had walked far enough, and so in a few minutes they turned round, and went towards home.
“Didn’t our gunpowder go pretty well, father?” said Rollo.
“Yes,” replied his father, “better than I expected it would, without being more accurate in our proportions.”
“It was a very good experiment, I think,” said Rollo.
“Yes,” replied his father, “it was a good experiment, and it will prove useful to you, if it impresses upon your mind the nature of that property of gunpowder on which its power depends; namely, that its combustion is within itself. It doesn’t need the outward air.”
“Yes, sir,” said Rollo.
“There are other things that are more inflammable than gunpowder; that is, they will take fire more easily, and make a greater flame; but they cannot burn unless they have air. There is phosphorus, for example; it will take fire a great deal more easily than gunpowder, and I believe it will make a greater flame; but it must have air, and it can’t burn any faster than fresh air can get to it.”
“Then phosphorus will take fire easier than gunpowder,” said Rollo’s mother.
“Yes,” said Mr. Holiday; “that is, with a less degree of heat. I presume that, if I were to rub phosphorus in a mortar, it would almost certainly take fire. These friction matches are made of some composition of phosphorus, and the heat of rubbing the end upon a board is enough to set the composition on fire. But gunpowder would not burn by being rubbed so. But still, though less heat is required to inflame phosphorus than gunpowder, still air is necessary for the phosphorus, and it is not necessary for gunpowder; so that gunpowder will burn in confined places when phosphorus will not.
“Suppose, for instance,” continued Mr. Holiday, “that we had a barrel of phosphorus and a barrel of gunpowder, both open at the top, and were to set them on fire. The gunpowder would burn at once from the top to the bottom at a single flash, without any help from the outward air. The phosphorus would take fire on the top, and burn down gradually, as fast as the air could come to the flame. It would burn very fast and furiously, and I think it likely it would make, in all, a greater flame than the gunpowder. But then it would burn gradually and only as fast as it could get a supply of fresh air; so that if, while it was burning, men were to come and cover it all over with wet blankets, so as to keep away the air, it would smother it, and put it all out.”