The burning phosphorus and other substances heat the match stick to the temperature at which it begins to burn; the burning match stick applied to paper heats the latter to the temperature at which it burns. The temperature to which a substance must be heated in order to burn and continue to burn is called the kindling temperature of that substance.
DRAFT; OXYGEN.--
EXPERIMENT 3: LACK OF DRAFT.--(a) Place a short candle on a pan. Light the candle and put a tall slender lamp chimney over it. Does the candle continue to burn? Why?
(b) Again light the candle and replace the chimney, but this time support it on two sticks of wood or on the handles of a knife and fork so that it will not rest directly on the pan. Place a saucer or a piece of cardboard over the top of the chimney. Does the candle continue to burn? Why?
EXPERIMENT 4: PRESENCE OF DRAFT.--Remove the cover from the top of the chimney, and again light the candle. Does it continue to burn? What substance necessary for combustion is present in the chimney? Explain why the candle soon went out in Experiment 3, but continued to burn in this experiment.
If a blanket is thrown upon a burning stick of wood, the wood soon ceases to burn. The wood stops burning because the oxygen of the air is excluded from it. The act of burning, i.e. combustion, is the union of any substance with oxygen, with the result that heat and light are produced. We have learned that a fuel cannot unite with oxygen until heated to a certain temperature. And, no matter how hot it is, the fuel will not burn unless it unites with oxygen. Oxygen, then, is the third requisite for combustion.
The necessity for a draft, i.e. a continuous supply of fresh air which furnishes oxygen, is shown by Experiments 3 and 4.
SAUTED [Footnote 4: To saute is to brown in a small quantity of fat.] SUMMER SQUASH [Footnote 5: See footnote 3.]
Wash summer squash. Cut it in slices 3/4 inch thick. (Do not remove the skin or the seeds.) Dip each slice in flour. In a frying pan put some fat and heat it. Add the squash and cook each slice on both sides until golden brown in color. Sprinkle with salt and pepper. Then place a cover over the frying pan and continue to cook the squash until it is tender. Serve at once.
BAKED WINTER SQUASH [Footnote 6: See "Note to Teacher," Footnote 3]
Wash a squash and cut or split it into pieces of suitable size for serving. Remove the seeds from each piece and make several gashes (at right angles to one another) cutting through the pulp down to the shell. Place the pieces (shell down) on the grating in the oven and bake (at moderate temperature) until the pulp is tender. Serve hot, with butter, salt, and pepper.
QUESTIONS
Name the three requisites for combustion.
Which has the higher kindling temperature, wood or coal? Explain your answer.
What is the price of summer and of winter squash? How much of each kind of squash is required to serve 6 persons?
LESSON IV
COAL RANGES [Footnote 7: NOTE TO THE TEACHER.--The principles of building a coal fire and of regulating dampers may be applied to furnaces and heating stoves as well as to kitchen ranges. In case there are no cooking or heating stoves or furnaces in which coal is burned in the homes of the pupils, this lesson may be omitted]--CORN DISHES
EXAMINATION OF A COAL RANGE.--Remove the lids from the coal range. Note the location of the fire box. What is its purpose? How is the floor of the fire box constructed? Where is the check damper? What is its purpose? Where is the ash pan? Where is the front damper? What is its purpose? Note the place where the stovepipe joins the range. What is the purpose of the stovepipe? Note the damper in the stovepipe. What is its purpose? Note the location of the oven. By what is the oven surrounded? Find the oven damper. Open it. In what direction do the hot gases pass out when the oven damper is open? What part of the range is heated when the oven damper is open?
An open damper permits a direct draft to pass through the range (see Figure 10).