Foods and home making

What is needed to build a fire? You have probably built a fire either in the woods, in the kitchen stove, of in the furnace. Regardless of where you build a fire, you must have something to burn. The dry leaves and branches used in the woods ; the coal, wood, or gas used in the home for firebuilding are fuels. A fuel is something that burns. We must have a fuel in order to build a fire. If you light a match and the burning match drops on the floor, you can put the match out by stepping on it. When you put your foot on the flame you keep the air away from the match. Then the match stops burning. All fuels need air (or oxygen, which forms a part of the air) to burn. The paper of this book is a fuel. There is air in contact with this paper. Why does the paper of your book not bum? In order to make paper or any fuel burn, it must be heated. When a fuel reaches a certain temperature, called its kindling tempera- ture, and is supplied with air, it starts to burn. A fuel must be heated to its kindling temperature in order to burn. The materials on the tip of a match have a very low kindling temperature. How is a coal fire built in a kitchen stove or furnace? The portion of the kitchen stove or furnace in which the wood, coal, and other fuels are placed is called the fire-box. The fire-box does not have a solid bottom. A grating forms the bottom of the box. If ashes have accumulated in the fire-box, they should be removed before starting to build the fire. Fuels should be placed on a clean grating so they may be supplied with air. Paper, which is easily heated to its kindling temperature, is Refrigerators — Stoves and Firebuilding 183 crumpled and placed in the bottom of the fire-box. Then sticks of wood are placed crisscross on the paper. A few pieces of coal may be placed on top of the kindling. Apply a lighted match to the paper. When the paper is heated until it reaches its kindling point, it burns. Then the wood burns, and finally the coal is heated to its kin- dling point and it burns. What is a draft ? We have learned that a fuel must have air in order to burn. It must have a constant supply of air. We also know that smoke arises from a fire. This smoke must pass out-of-doors through the chimney. Thus the fire in the kitchen stove or furnace must have a constant supply of air and an outlet for the smoke. We say that a draft is needed to make a fire burn in a stove or furnace. Let us do some experimenting to learn what a draft is : Figure 62. Fire-Box of Coal Range The air that must be furnished to a burning fuel enters the stove at the back of the fire-box as indicated by the row of arrows. It circulates around the box and up through the grating. Experiment 13 : To show how to arrange a draft. (a) Hold a lighted match to the bottom of a candle so as to melt the candle slightly. At once stand the candle upright on a pan or saucer. Light the candle. Over it hold a tall slender chimney so there is about \ inch space between the pan and the bottom of the candle. Does the candle keep on burning after the chimney is held over it? ( b ) Continue to hold the candle as directed in (a). Place a saucer or a piece of cardboard on top of the chimney. Does the candle con- tinue to burn? Explain the behavior of the candle.