Why is there less water in the soil in summer than in winter, and where does it exist?
What holds it in its vapory form?
How is it affected by cold substances?
Describe the deposit of moisture on the outside of a pitcher in summer.
What other instances of the same action can be named?
It is well known that a cold pitcher in summer robs the vapor in the atmosphere of its heat, and causes it to be deposited on its own surface. It looks as though the pitcher were sweating, but the water all comes from the atmosphere, not, of course, through the sides of the pitcher.
If we breathe on a knife-blade, it condenses in the same manner the moisture of the breath, and becomes covered with a film of water.
Stone houses are damp in summer, because the inner surfaces of the walls, being cooler than the atmosphere, cause its moisture to be deposited in the manner described. By leaving a space, however, between the walls and the plaster, this moisture is prevented from being troublesome.
How does this principle affect the soil?
Explain the experiment with the two boxes of soil.