Science for beginners . n the burnerinstead of above the burner as it should. If the supply ofair is insufficient, the flame will be luminous and smoky. The air supply on a gas stove should be carefully watchedand frequently regulated to secure the best results. Fireless Cookers 143. Cooking Temperatures.—The cooking of foods is ac-complished by raising them to a certain temperature and then DEVELOPMENT OF COOKING DEVICES 131 maintaining that temperature for a certain length of the temperature required and the time required vary,first, with the nature of the food to be cooked, and se
Science for beginners . n the burnerinstead of above the burner as it should. If the supply ofair is insufficient, the flame will be luminous and smoky. The air supply on a gas stove should be carefully watchedand frequently regulated to secure the best results. Fireless Cookers 143. Cooking Temperatures.—The cooking of foods is ac-complished by raising them to a certain temperature and then DEVELOPMENT OF COOKING DEVICES 131 maintaining that temperature for a certain length of the temperature required and the time required vary,first, with the nature of the food to be cooked, and second,whether it is to be cooked wet, , stewed or boiled, orcooked relatively dry , baked. Stewing and boilingusually require a temperature near the boiling point of water,or from 180° to 212°F. Baking requires a much highertemperature. Bread is commonly baked at about 375°F. 144. Conductors and Non-conductors.—If it were possibleto discover a device which would entirely prevent the loss of If) STOP ON BAi. ALUMINUM BAND ABOUND 8AKING OlSKS / Fig. 100.—A lireless cooker. heat, it is evident that it would be necessary only to bring thefood once to the proper temperature; if no heat were lost,the food would then remain at that temperature indefinitelyor until cooked. Unfortunately we know of no means ofpreventing heat from escaping through the walls of anyvessel we can construct. Heat passes through every knownmaterial. However, it passes through some materials muchmore readily than through other materials. Materialsthrough which heat passes readily are said to be good con-ductors of heat; materials through which heat passes lessreadily are said to be poor conductors of heat. All metals 132 THE PRODUCTION AND USE OF HEAT are good conductors of heat; air, asbestos, and paper are poorconductors. 145. Fireless Cookers.—Fireless cookers are constructedof materials which are poor conductors. They are usuallyvessels of box-like construction with thick wal
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