Boxes to be filled with the first class of insulating materials are
packed in the following manner:
Line the box and cover, smoothly, with one thickness of heavy paper, or
several thicknesses of newspaper. This will prevent cold air from
finding its way through the cracks, and dust and pieces from sifting
out. Asbestos sheeting also makes a good lining. Pack in the bottom of
the box a firm layer of insulating material not less than three or four
inches in depth. This must raise the cooking pail to within from three
to five inches of the top of the box. Set the utensil in the middle of
the space allowed for it on this layer, and pack around it, very
tightly, until level with the top of the kettle. When this is removed it
will be found to have left a hole just large enough for it to slip into
again. A little manipulation will make the rim of this pocket less
ragged than at first. The cushion for boxes packed with excelsior or hay
should be at least four inches thick. In packing with paper, lay first
an even layer three or more inches thick of folded papers, filling the
space around the kettle with soft, crumpled papers. In place of the top
cushion, make a bundle of papers folded to just the right size. This can
only be done when perfectly flat pail covers are used, unless a
supplementary soft cushion be first laid over the pail.
The box is now ready for cooking, but if, after considerable use, the
material shrinks so that the whole space is not firmly filled, a little
more may be added. There should always be at least a slight pressure
when the cover is closed. The paper lining described on page 20, while
not necessary to this class of boxes, is an improvement.
[Illustration: Figure No. 2.