The ovens of a number of ranges are equipped with thermometers. Although it is possible to secure more satisfactory results with a thermometer than without, oven thermometers do not always indicate the temperature of an oven accurately. If a thermometer is fastened on an oven door, for example, and the door does not heat as quickly or to as high a degree as the interior of the oven, the true temperature of the oven cannot be ascertained by this device. By making allowance for the difference, however, such a thermometer may prove very useful. It is much more accurately and conveniently read than a thermometer which is hung or rests inside the oven unless the oven is provided with a glass door.
A device known as an "Oven Heat Regulator" may be attached to gas ranges. These devices do not merely measure the heat of an oven, but control it and keep the oven temperature constant. A "temperature wheel" is set for a desired temperature and the oven burner lighted. By the expansion or contraction of a sensitive copper tube placed in the top of the oven the gas valve is opened or closed. When the valve is opened the amount of gas burning is increased or decreased so that the temperature of the oven is kept constant, i.e. at the temperature at which the wheel is set. Insulated ovens, i.e. ovens which are constructed so as to retain heat and allow little to escape, are found on some of the modern gas, electric, and kerosene stoves. Some of the insulated electric ovens are provided with clocks or dials which may be adjusted so that the current is cut off automatically at the expiration of a certain length of time, or when a certain temperature is reached. Because of the insulated walls on such ovens, the food continues to cook on "stored heat."
A chemical thermometer inserted in an oven is a fairly satisfactory means of obtaining oven temperatures.
Baking temperatures have been classified as follows:
1. Slow oven (250 degrees to 350 degrees F.) for custards and meringues.
2. Moderate oven (350 degrees to 400 degrees F.) for bread, gingerbread, plain cake (the lower temperature should be used for loaf cakes and the higher temperature for layer cakes), all molasses mixtures.
4. Very hot oven (450 degrees to 550 degrees F.) for pastry. After the first 6 minutes, the temperature should be lowered to "hot."