=52. Directions for Using the Cooker.= Put the stones on to heat. Prepare the food as for cooking in any other way. Then heat it, either in the oven or on top of the stove. It is preferable to heat the food in the same vessel in which it is to be cooked in the fireless cooker. Transferring food to a cold vessel entails a loss of heat, since the first vessel is already heated. [Illustration: FIG. 23. Devices for fireless cooker.] When the stones and food are hot, place the stone in the bottom of the cooker. Put in any asbestos mats or other devices which are needed to protect the food. The stone should be hot enough to respond to the test for flat irons. It should make the snappy noise of a good hot iron when the finger is moistened and touched to it. Place the food in the cooker. Place another stone above the utensil if it is desirable to have the food brown on top. Close the fireless cooker, and let it stand until ready for use. [Illustration: FIG. 24. Gas cookers.] =53. Time of Cooking Food.= Six hours or over night should be allowed for the cooking of cereals. Stews should be given two to three hours' time for cooking. Large roasts and hams require five to six hours. It is sometimes necessary, when they are large, to remove them and heat the food and the stones on the stove once during the process of cooking. Dumplings and angel cakes cook well in a fireless cooker. So do all dried peas and beans. [Illustration: FIG. 25. Steam cooker.] It is profitable to cook foods requiring more than forty minutes' heating in a fireless cooker. The heating unit is a part of some cookers. Electric cookers, instead of being furnished with stones to be put inside the nest, have a heating unit and plate for holding heat in the cooker. Cold food may be put into this cooker, the current turned on, and the heating and cooking all be done inside the cooker. The electric oven which is well insulated answers the purpose of a fireless cooker when the current is disconnected. Either a thermometer, which the housewife may watch, or thermostat, which controls the current, must be attached to electric cookers to prevent burning the food or injuring the cooker with too much heat. =54. Gas Cookers.= Since heated air rises, special cookers in the form of insulated caps are made to put over dishes of food heated on gas burners (Fig. 24). The inside of the cap must be kept clean. Get the dishes hot with the cap suspended over the food, but leaving about an inch space for the escape of gases from the heating unit. As soon as the food and cap have been sufficiently heated over the fire, turn off the gas and lower the cap so that it will retain the heat. After the cooker has been used, it should be wiped out clean; otherwise it will retain some of the odors of the cooked food.