Q. How can the pressure of steam on the surface of the water, force the water through the kettle-spout?
A. In the same manner as the pressure of air on the mercury of a barometer, forces the quicksilver up the glass tube.
Q. What causes the rattling noise so often made by the lid of a saucepan or boiler?
A. The steam (seeking to escape) forces up the lid of the boiler, and the weight of the lid causes it to fall back again: this being done frequently, produces a rattling noise.
Q. If the steam could not lift up the lid of the boiler, how would it escape?
A. If the lid fitted so tightly, that the steam could not raise it up, the boiler would burst into fragments, and the consequences might be fatal.
Q. When steam pours out from the spout of a kettle, the stream begins apparently half an inch off the spout; why does it not begin close to the spout?
A. Steam is really invisible; and the half-inch (between the spout and the “stream of mist”) is the real steam, before it has been condensed by air.
Q. Why is not all the stream invisible, as well as that half-inch?
A. As the steam comes in contact with the colder air, the invisible particles (being condensed), roll one into another, and look like a thick mist.