|
Lecture Four |
|---|
|
When an object burns, some of the oxygen in the air is used up. Only about one fifth of air consists of oxygen and we can make objects burn much faster and hotter if we burn them in pure oxygen instead of in ordinary air. This is just one of the many uses of pure oxygen. |
|
If a person who is ill has difficulty in breathing, he will not take in enough oxygen. We can help him to get better more quickly, by letting him breathe more oxygen than air contains. But it is not only sick people who need more oxygen. Men who climb high mountains and pilots who fly very high in airplanes also find difficulty in breathing. This is because there is less air and therefore less oxygen high in the atmosphere. But they have no problems when they carry containers of pure oxygen on their backs. These containers add oxygen to their air which is then breathed through a mask worn over the nose and mouth. |
|
In the same way if we go into places where the air is very dirty, such as deep underground in a mine, or in parts of a chemical factory, then we need oxygen masks. Also when we do sport we use up oxygen faster than usual. So, for example, breathing more oxygen can help a runner to run faster. |
|
KEY PARAGRAPH |
|---|
|
Uses of Oxygen |
|
Only about one fifth of air consists of oxygen. However, pure oxygen is used in many ways. We let sick people breathe more oxygen than air contains. Also, men who climb high mountains carry containers of pure oxygen. If we go down a deep mine, we need oxygen masks. |