Page:Alcohol, a Dangerous and Unnecessary Medicine.djvu/79

Rh coals; when this combination takes place a great deal of heat is given off. The same thing is true of our bodies; in order that food matters may be burnt in them and enable us to work and keep warm, they must be supplied with oxygen; this they get from the air by breathing. We all know that if his supply of air be cut off a man will die in a few minutes. His food is no use to him unless he gets oxygen from the air to combine with it; while he usually has stored up in his body an excess of food matters which will keep him alive for some time if he gets a supply of oxygen, he has not stored up in him any reserve, or, if any, but a very small one, of oxygen, and so he dies very rapidly if his breathing be prevented. In ordinary language we do not call oxygen a food, but restrict that name to the solids and liquids which we swallow; but inasmuch as it is a material which we must take from the external universe into our bodies in order to keep us alive, oxygen is really a food as much as any of the other substances which we take into our bodies from outside, in order to keep them alive and at work. Suffocation, as death from deficient air supply is named, is really death from oxygen-starvation."— Martin's Human Body.

Much of the food taken into the body is burned to supply energy and heat. This burning is called oxidation. When food is burned, or oxidized, either in the body, or out of it, three things are produced, carbon dioxide (carbonic acid gas), water and ashes. These are waste matters, and must be expelled from the body, or they will clog up the various organs, as the ashes and smoke of an engine would soon put its fire out if they were allowed to accumulate in the furnace. It is the duty of the lungs to pass the carbon dioxide out to the air. With every breath exhaled, this poison gas, generated in the body through the oxidation of food,