Air and Water?

Air and water are two materials with which everyone is familiar. We live at the bottom of an ocean of air, called the atmosphere. Air surrounds our bodies every minute of our lives, expect when where swimming and bathing. Air may be found almost open hallow in all materials on the surface of the earth. There is air also in many of the hallows and opening of the human body-for example,  our ears, mouth, nose and lungs. All animals breath air, and if deprived of it, they die.

     The waters of seas, lakes, rivers, and streams, cover three-quarters of the earth's surface. Water is necessary for life. The cells of which living things are made are largely water. Water, given enough time, will dissolve almost any substance. this is important, because the materials that nourish living things are dissolved in water. This water makes up the main part of the blood of animals and the sap of plants, the two fluids that carry nourishing materials to cells of living things.

     We shall perform experiments concerning both air and water, because, as we shall see, these two materials are closely connected in many ways.