It is estimated that 90 per cent of heat supplied for baking in ovens is lost through the sides of the oven. A considerable saving of heat can be effected by insulating the oven, as is done in the case of most electric and some gas ovens. An ordinary gas oven may be fairly well insulated by means of sheet asbestos cut to fit all the sides with the possible exception of the one occupied by the door, and attached by wires to the corners of the oven.

The so-called automatic cookstove, or insulated oven, has the advantage over the ordinary fireless cooker of being still more eco-. nomical in regard to heat and labor and of eliminating an additional piece of equipment in the kitchen, because, as ordinarily made, it has top burners also, and hence takes the place of the usual range. In the commercial insulated oven, both the preliminary heating of the food and the complete cooking process are accomplished; consequently, both the loss of heat occasioned by transferring the food container from the stove to the cooker and the labor of this motion are eliminated. Moreover, the walls of the oven itself are heated and do not draw the heat from the food. There are now on the market insulated ovens adapted to the use of gas, electricity, and kerosene. The heat supply in some of these ovens is controlled by a dial hand that may be adjusted for the number of minutes for which the heat is required, at the end of which time the heat is cut off without further attention. A large insulated oven, modeled somewhat like an ordinary gas stove, is more expensive than is a fireless cooker; but the cost of a moderate-sized range with an insulated oven is practically the same as that of both a gas range and a fireless cooker. This is a subject worthy of investigation by one who is purchasing new kitchen equipment.