Does the idea appeal to you of putting your dinner on to cook and then
going visiting, or to the theatre, or sitting down to read, write, or
sew, with no further thought for your food until it is time to serve it?
It sounds like a fairy-tale to say that you can bring food to the
boiling point, put it into a box of hay, and leave it for a few hours,
returning to find it cooked, and often better cooked than in any other
way! Yet it is true. Norwegian housewives have known this for many
years; and some other European nations have used the hay-box to a
considerable extent, although it is only recently that its wonders have
become rather widely known and talked about in America. The original box
filled with hay has gone through a process of evolution, and become the
fireless cooker of varied form and adaptability.
Just what can we expect the fireless cooker to do? What foods will it
cook to advantage?
Almost all such dishes as are usually prepared by boiling or steaming,
as well as many that are baked--soups, boiled or braised meats, fish,
sauces, fruits, vegetables, puddings, eggs, in fact, almost everything
that does not need to be crisp can be cooked in a simple hay-box. If the
composition of foods and the general principles of cookery are well
understood, but little special instruction will be needed to enable one
to prepare such dishes with success; though even a novice may use a
fireless cooker if the general directions and explanations, as well as
the individual recipes, are carefully read and followed. While such
dishes as toast, pancakes, roast or broiled meats, baked bread and
biscuits, are impossible to cook in the simpler form of hay-box, the
insulated oven, the latest development of the fireless cooker, opens up
possibilities that may lead to a much wider adaptation of home-made
insulators to domestic purposes. Roast meats, however, may first be
cooked in the oven and completed in the hay-box or cooker, or they may
be cooked in the hay-box till nearly done and then roasted for a short
time to obtain the crispness which can be given only by cooking with
great heat.
During ordinary cooking there is a great loss of heat, due to radiation
from the cooking utensil and escaping steam. If, however, this heat
could be retained, the food would continue to cook in the absence of
fire. This is what occurs in the hay-box. Hay, being a poor conductor of
heat, will, if closely packed around a kettle of boiling food, maintain,
for a number of hours, a sufficiently high temperature to continue the
cooking process. The familiar practice of using newspapers or carpet in
keeping ice from melting depends upon the same principle. In both cases
a material which is a poor conductor of heat, when interposed between
the surrounding air and articles which are either colder or hotter than
the air, being found to preserve their temperature. Other materials than
hay or papers will act in the same way; such, for instance, as
excelsior, sawdust, wool, mineral wool, and others. A vacuum will have
the same effect as insulating materials. The “Thermos Bottle” and
similar inventions, which are glass bottles surrounded by a vacuum and
contained in metal cases, will keep foods hot or cold for many hours. If
heated with a little boiling water before boiling food is poured in they
will even cook some foods satisfactorily. A vacuum is expensive, as it
is difficult to obtain, and therefore the ordinary fireless cooker is
better suited to every-day use; but if one of these bottles is at hand
it may be utilized in cases of illness or on journeys or in other
unusual circumstances, when a cooker is not available.
The general trend of recent scientific investigation seems to indicate
more and more clearly that the prevalent idea that all food must be
cooked at a high temperature, such as that of boiling water (212 degrees
Fahrenheit), is a mistaken one. Experiments have shown that starches are
made thoroughly digestible at temperatures varying from 149 degrees to
185 degrees Fahrenheit. Cellulose, the woody fibre of vegetable foods,
becomes perfectly softened at a temperature considerably below 212
degrees, while albuminous materials, of which all animal and many
vegetable foods are largely composed, are not only well-cooked at a low
temperature, but are decidedly more easily digestible than when cooked
at the higher temperatures of boiling or baking.