Q. Why do tiles, stones, and rocks often split in winter?
A. Because the moisture (which they imbibed) freezes, and by its expansion splits the solid mass.
Q. In winter time, foot-marks and wheel-ruts are often covered with an icy net-work, through the interstices of which the soil is clearly seen,—Why does the water freeze in net-work?
A. The water in these hollows froze first at the sides of the foot-prints: other crystals gradually shot across the water, and would have covered the whole surface, had not the earth absorbed the water before it had time to freeze.
Q. In winter time these foot-marks and wheel-ruts are sometimes covered with a perfect sheet of ice, and not an icy net-work,—Why is this?
A. The air being colder and the earth harder (than in the former case), the entire surface of the foot-print is frozen over, before the earth can draw the water in.
Q. Why is not the ice solid in these ruts?—why is there only a very thin film or net-work of ice?
A. Because the earth absorbs the water, and leaves the icy film behind.
Q. Does not water expand by heat as well as cold?