A few minutes before the food is to be removed from the open burner, the current should be turned off, as the heat in the stove will continue the cooking for several minutes. From tests of electric stoves, it appears that in most of them the food will continue to cook after the switch is turned off for about the same number of minutes that it requires to raise the heating unit to a temperature sufficient to boil water in a small shallow pan. A housekeeper who is using electricity for cooking can soon learn how long the open burners and oven of her stove will keep food cooking after the current is turned off, and by putting this information to use, she can save many dollars in a year. =39. Care of Electric Stoves.= When thru with a stove, always turn off the current. Great care should be taken that the stoves do not become overheated. This shortens the life of the stove. Sudden cooling of the coils of wire caused by liquids spilling on them, and corrosion of the wires caused by dampness, wear out stoves faster than need be. Do not wash or brush dirt from burners having open coils of wire. Burn all dirt from the burners. =40. Utensils for Electric Stoves.= The most economical use of electricity can be secured with utensils built around the heating units (Figs. 20 and 21), and the next most economical use with utensils built especially to fit the heating units. This means that there would be a heating unit for each utensil, or size of utensil, and the expense of equipment would be considerable. Also, more care would be needed in washing the utensils and in preventing them from becoming bent. Such facts must be considered in choosing between stoves with special devices and those on which any pan may be set. After installing an electric stove, start with new utensils because they will not blacken on an electric stove, and so can be washed with the other dishes. [Illustration: FIG. 21. Utensil with heating unit.] When ordinary household utensils are used, they should be of such shape that they stand flat, as they also should on a coal range. The most economical use of heat is secured when the area of heat is smaller than the area of the bottom of the kettle and is concentrated on the utensil. Care should be taken when stoves are installed, that they are properly grounded so that they cannot burn any one. A light bulb is attached to some stoves so that when the current is on the light burns, and when it is off, the light goes out. Such a light should be on all large stoves. =41. Detachable Cooking Devices.= Cooking and heating devices should have larger wires than those for lighting alone. Consequently, the attachment of a heating device in a common light socket may cause burning out of fuses or other damage. One danger in using detachable electric devices occurs in not turning off the current when the stove is not in use, thus permitting it to become overheated. This shortens the life of the stove.