The idea of a special box for conserving heat for cooking purposes seems to have originated in Norway.
The fireless and the steam pressure cookers rank highest in value among the comparatively new devices for food preparation and preservation.
Each has its own particular usefulness, but both conserve time, fuel, and strength, and thus help toward enabling the housewife to take some part in activities outside the kitchen.
Fireless cookers have been widely used for several years; steam-pressure cookers have won their way into many kitchens following the increase in the home preservation of food.
An effort is now being made to bring both these devices into year-round, every-day usefulness and so increase their value to the housewife who already owns them or to the one who contemplates buying them.
The discussion of each device is taken up separately in order to avoid confusion.
The Fireless Cooker
Within the last ten or fifteen years so much ingenuity has been exercised in perfecting the construction of fireless cookers, that there is no longer any question as to their worth.
Reasons for Using a Fireless Cooker
The fireless cooker not only saves time and fuel but also gives a better flavor to many products, and may make them more easily digested than would be possible by other types of cooking. In certain households where no outside help is employed, either a homemade or a commercial fireless cooker may become an almost indispensable piece of equipment.
Economy of fuel
Under present conditions the use of the fireless cooker is likely to become more general as a means of saving fuel. There are, however, conditions under which the use of the fireless cooker may not save fuel, hence a knowledge of when to use the cooker is necessary.
If a coal fire must be built in order to accomplish the initial heating of the food, and if this fire without replenishment of fuel would complete the cooking process, there would obviously be no saving in fuel effected by the use of the fireless cooker.
However, there might be a saving in time and labor, as discussed further on.
Although a slow, even heat may be maintained with kerosene, gas, or electric, stoves at a comparatively low cost, for most processes the amount of heat needed to bring the food and the radiator to the required temperature before they are placed in the fireless cooker, is generally much less than the amount needed to cook the food on the stove.
The longer the cooking process is to be continued, the greater is the saving of fuel by supplementing a kerosene, gas, or electric, stove with the fireless cooker.
It is possible, in fact, to save as much as thirty or more cubic feet of gas by the use of a fireless cooker in cooking such foods as cereals, beans, tough cuts of meat, or steamed puddings which require about three hours of cooking on the ordinary stove.
Economy of time and labor
For many persons the present high cost of living necessitates obtaining the most nutriment at the lowest cost. The nutritious foods at low cost, such as cereals, legumes, and tough cuts of meat, are those that require long, slow cooking to be made most palatable and of greatest use to the body.
The high cost of fuel often makes these foods as unavailable as are the more expensive foods. Under such conditions the fireless cooker is almost a necessity if the family is to be properly nourished.
If fuel is being burned, there is always more or less uneasiness about leaving the house or the room in which food is being cooked. The amount of heat may vary or the food may be forgotten, with the result that the food may stick to the bottom of the utensil and burn. This gives a poor product and makes dishwashing a difficult task.
The fireless cooker makes it possible to leave the food without worrying about the results. Thus, other occupations may be carried on while the food is cooking. In households where it is necessary for the woman to be away from the home all day, the fireless cooker helps to solve many problems of meal preparation.
However, as stated further on, there is a certain point at which the cooked product is at its best and should be removed from the cooker.
The fireless cooker is found to be a time-saver when the various members of the household have their meals at different hours because food may be kept hot in it until each member is ready to be served.
With the limited cooking surface of an oil or gas stove, it is often difficult to, have all the dishes for the meal cooked and ready to serve at the same time.
In this case a fireless cooker may be used for keeping some of the food hot while the remainder of the meal is cooking.
The fireless cooker may prove the most satisfactory kind of “hired help” for the woman on the farm whose work often includes helping in the fields and about the farm buildings as well as preparing meals and performing other household tasks.
The fact that the cooking process need not be interrupted during transportation has led to the use of the fireless cooker by armies on the march; at the end of the journey the meal is ready to be served.
It is often so used by camping and picnic parties. When the men of the farm are to be absent all day in fields at some distance from the house, the fireless cooker may be loaded in the farm wagon and taken along in order that a hot meal may be enjoyed at the noon hour.
In the preparation of the hot lunch in rural schools the fireless cooker, which may be made by the boys of the school, has proved its usefulness. The cooking of the hot dish may be started before school or at the morning recess and requires no attention during study hours.
Principles of Fireless Cooking
Food to be cooked in a fireless cooker is first thoroughly heated; it is then placed in the cooker either with or without a heated stone or radiator underneath, and the stored heat is locked up and utilized for cooking instead of being allowed to escape.
The principle underlying fireless cooking is the maintenance, for a certain period of time, of a fairly constant temperature, high or low, by surrounding the compartment in which the food is placed with material which tends to prevent the passage of heat. Materials which may be used for this purpose are called insulators.
Use of insulating substances
Certain substances are better conductors of heat than are others. Metals are good conductors of heat, while non-metals are poor conductors of heat. The metal container in which ‘food is placed on the stove conducts the heat from the fire to the food.
When the food is sufficiently heated, it is quickly transferred in the container, from the stove to the food compartment in the fireless cooker. This compartment is surrounded by insulating, or non-heat-conducting, substances which tend to prevent the heat escaping from the food and to keep it at a fairly constant temperature for some time.
The better the insulating substance and the construction of the fireless cooker, the greater will be the amount of heat retained and the longer will be the period of time for which it may be held.
Cotton, wool, felt, sawdust, cork, mineral wool, silk, flannel, paper, wood, cotton cloth, and asbestos are the best insulating substances.
Heat passes through air with the greatest difficulty but it may be carried from a heated substance by waves or currents of air. Air, then, is best used as an insulator when it fills the space between small particles of substances of low heat-transferring power. The particles of materials such as excelsior, hay, newspapers, sawdust, cork, and asbestos prevent the air waves or currents from carrying the heat away from the heated material, and are, therefore, most commonly used as insulating substances in fireless cookers.
A complete vacuum is the most effective insulator. It is used in thermos bottles and in certain fireless cookers.
Application of the principle of fireless cooking
Primitive people have made use of leaves and earth to prevent the escape of heat from food being cooked by means of hot stones or hot ashes.
Campers, who necessarily employ the more primitive ways of cooking can testify to the long time that heat can be retained by covering hot ashes with earth.
The bean hole of lumber camps continues the cooking of parboiled beans for twelve or fourteen hours by the heat stored up in the food, the bean pot, and the stone, and retained by a covering of earth.
Feathers have been used as an insulating substance by the peasant folk of certain countries; they have followed the practice of placing kettles of boiling soup in feather beds, thus keeping the soup warm overnight.
Points to be considered in buying a fireless cooker
Many good types of fireless cookers are on the market. They may have advantages over certain types of homemade cookers in sanitation, insulation, provision for escape of steam, and in appearance.
Escape of heat
The more perfectly the cooker is insulated, the better are the results. There are certain trade mixtures of insulating materials, the secrets of which are not divulged. However, a reliable manufacturing company may be trusted to offer a good product.
Exterior of case
Attention should be paid to the durability of construction, and to the ease and thoroughness with which the cooker may be cleaned. The outer case may be made of well-seasoned and well-finished hardwood, or of metal. Wood is better than metal as a non-conductor of heat, but metal is more easily cleaned.
Interior of lining
The material used for lining the interior should be durable and such that it may be cleaned easily and thoroughly. Seamless aluminum, nickel-copper, and enamel are used for this purpose. The old models containing flannel-covered cushions were distinctly inferior to the present models that have nothing but metal exposed on the interior and are consequently non-absorbent and easily cleaned. In this respect the homemade cooker is often deficient.
The care of a fireless cooker
Like all other pieces of equipment, a fireless cooker gives greatest satisfaction when properly cared for.
Prevention of odors
The interior of the fireless cooker should be kept absolutely clean. It should be washed, dried, and sunned, if possible, each time after being used. It should remain open several hours after use, and it should never be tightly closed when not in use. The observance of these precautions prevents the food from acquiring an unpleasant taste from odors or remnants of food previously cooked.
For convenience all equipment to be used in connection with the cooker, such as hot plates, hooks, racks, and cooking utensils, should be kept near the cooker. A shelf, cupboard, or an improvised cabinet made from a box may serve as a convenient storage place.
The soapstone radiators, when not in use, may be kept warm on the back of the stove or in the sun, in order to reduce the length of time required to bring them to the desired temperature when they are needed.
Where to keep the cooker
The cooker itself should be placed near the stove, both to prevent unnecessary loss of heat in transferring the food from the stove to the cooker and to save labor on the part of the worker.