Figure No. 6.
1. Method of tying slip-knot. 2. Method of tying the cover on a pail.
Obviously, this arrangement will work equally well in keeping cold foods cool in summer, such as ice water, or cool drinks. Even frozen creams and ices, if packed well in a mould, covered tin pail or can, sealed and surrounded with a small quantity of ice and salt, and the whole thus insulated, will keep for many hours. To seal the mould, dip a narrow strip of muslin in melted fat and lay it quickly over the crack between the cover and mould.
III
THE REFRIGERATING BOX
As we have seen in the case of the insulating pail, the principle involved in cooking by retained heat may be reversed, and the heat may, by similar means, be excluded from foods which are to be kept cold. Ice-boxes and refrigerators are made with this end in view. They are constructed with heavy walls, usually, if not always, with an interlining of some non-conducting material, to exclude the heat of the atmosphere. Where such an article is needed permanently, or for large quantities of food, the various refrigerators on the market are better adapted to the purpose than a home-made box. But, in cases of temporary necessity or to supplement a refrigerator, the home-made refrigerating box will doubtless find a use. Ingenuity will suggest variations in the manner of applying the principle of insulation to keeping foods cold, but by way of suggestion two forms of refrigerating boxes are described below.
Refrigerating box packed with three crocks.
Take three or more stoneware crocks with well-fitting covers of the same material. The size of the crocks must be determined by the quantity of food to be kept. Good results in the way of temperatures have been obtained with those holding a half gallon, but the amount of food accommodated in them is, of course, small.
Proceed exactly as for packing a cooker, except that the crocks must be set in place so that all of them touch the central one, which is to be filled with ice.
Although any insulating material suitable for cookers will answer for a refrigerating box, sawdust will be found the easiest to handle, for the reason that its fine particles will more readily fill the acute angles between the crocks, which must be carefully packed or the insulation is not complete. It will be best to make one narrow cushion that may remain in place over the central crock, except when the ice is to be renewed, and two others, each of which can be removed singly when the crock under it is to be opened. Put the food into dishes or pails that can be removed with it and washed. This will obviate the necessity for taking out the crocks frequently and will mean a considerable saving of ice. In lieu of one solid piece of ice, broken pieces will be found to answer excellently. Fill the ice-crock as full as possible, and do not open it until it needs refilling. A little observation of your own individual box will be necessary to tell you just how long your crock of ice will last. It will probably be safe, in any case, to leave it two full days after filling it before opening it. If no foods that have not been reasonably cooled are put into the refrigerating box it is possible that the ice may last three or four days.