Q. Why does it feel so cold, when it rests on the fender?
A. Not being so warm as our hand, it imbibes the heat from it with such rapidity, that our loss of heat is palpable, and produces the sensation of coldness.
Q. Why are flues (which are carried through a church or room) always blackened with black lead?
A. In order that the heat of the flue may be more readily diffused throughout the room. Black lead radiates heat more freely than any other known substance.
Q. Why do country people touch the thick end of an egg with their tongue, to know if it be stale or not?
A. The thick end of an egg always contains a little air (between the shell and the white); but, when the egg is stale, the white shrinks, and the air expands.
Q. How can the tongue tell from this, whether the egg be stale or fresh laid?
A. As air is a very bad conductor, if the egg be stale, it will feel much warmer to the tongue, than if it be new-laid.
Q. Why will the big end of an egg feel warmer to the tongue, because it contains more air?