Tom. Not at all, father. When you told us about the expansion of cold water below forty degrees, we wondered, because we could not think ice was more bulky than water; but there seems no reason to doubt, that the hotter water becomes, the more room it takes up.
Mr. W. How does the heat of the fire do this?
Tom. By expanding it.
Mr. W. We know that; but how?
Tom. By driving the particles of steam farther and farther asunder.
Mr. W. Precisely. The moment the particles of a drop of water become steam, they occupy eighteen hundred times as much room as they did before.
Tom. And press the lid eighteen hundred times more forcibly than water?
Mr. W. Its force is altogether irresistible. If this kettle were composed of iron, an inch thick or more, if steam could not escape, it would burst it with ease.
Tom. Is that the reason why steam boilers burst?
Mr. W. It is one reason, but not the principal one. If the water in the kettle were all boiled out, and it was full of steam, and we corked it tightly up, and soldered the lid down, and still kept the fire blazing fiercely about it, it would burst at the weakest part: perhaps the lid would fly off, or the side burst: the steam would rush out, and, if we were near, we might be scalded.