THREE FORMS OF WATER.
We have seen that water is necessary to the life of plants and animals. Now let us try to find out something about the properties of water.
There are three different forms which water takes. Each is very unlike the others. They are so unlike that if we had not seen one change into another we should hardly believe that they were different forms of the same thing.
There is first the common form. You all know this one, it is the water which we drink. If we go far enough in any direction we come to water. It forms all the streams and lakes as well as the great oceans. There is more water than anything else upon the surface of our earth.
Water is a liquid. By liquid we mean some thing that can be poured. We take a cup of water and pour it into a basin. It takes the shape of the hollow in the dish that holds it. A solid does not act in this way. It keeps its shape.
Water is not the only liquid. There are many others. have many substances which form solids at the ordinary temperature, but if they are placed in a very hot place they become liquid. The heavy mineral we call lead is a solid. It is useful in making water pipes and shot. If we heat lead it melts easily and becomes a liquid. It can then be poured like water.
There is another form of water called steam or vapor. When water is heated it changes to steam. The particles of water forming the steam are so small that if you could look into an engine boiler you could not see them. When the steam comes out of the engine into the cool air the little particles run together and form others large enough so that they can be seen. Now we have a dense white cloud about the engine.
When water is changed to steam it takes up very much more room than it did before. Each of the tiny particles of water in the steam is very warm.
It wants lots of room. Each one pushes against his neighbors as hard as he can. This is why the lid of the tea-kettle jumps up and down.
When steam is shut up tight we • can make it work for us. The little particles push with such strength that they can make the wheels of a heavy engine turn around, and draw a long line of loaded cars.
There are tiny water particles all about us in the air. They are invisible except when they turn into clouds or fog. At night they form the dew which makes the grass so wet.
The third form of water is ice. When water becomes very cold it turns to a solid substance which we call ice. We all know how clear and smooth ice is. We cool our water with it upon hot summer days, and in winter we skate over its slip pery surface. The children of warm climates do not know the pleasure of skating. Where do you suppose the ice comes from that is used where it is never cold enough to freeze water ? We call ice frozen water. When the air becomes warm the ice begins to melt. In a little time a cake of solid ice will change to water.
When water freezes it wants a little more room than it did before. This is why your pitcher is broken when the water in it freezes.
Hailstones are frozen raindrops. The drops of water falling through the air sometimes become so cold that they turn to ice.
Can you tell what the pretty snowflakes are made of? They are frozen clouds. They fall very gently and make everything pure and white. Each flake has six sides or points like a star.
If you live in the South and have never seen the snowflakes get your papa to take you to the mountains when the winter storms come.