Either granulated or pulverized sugar may be used, but pulverized is the better of the two, because it is lighter. When the sugar is added at this time, sift the flour several times, and, as in Fig. 6, add it last, folding it into the mixture with a wire egg whip. However, if it is desired to do so, the sugar and flour may be sifted together and added at the same time, or both the sugar and flour may be sifted separately and then added to the eggs alternately. Then add the flavoring and, if liquid is to be used, put it in at this time. In case leavening is supplied, sift it in with the flour. The mixture is then ready for the pan. Place the ungreased pan conveniently on the table and then, as shown in Fig. 7, pour the mixture from the bowl into it. Scrape the sides of the bowl well, so that there will be no more waste than is necessary.
42. BAKING SPONGE CAKE.--As soon as the mixture has been poured into the pan, set it in a moderate oven to bake. The temperature should be about 300 degrees Fahrenheit when the cake is put into the oven, but it may be gradually increased to 350 or 400 degrees. If the temperature cannot be determined, the paper test may be applied. This consists in placing a piece of white paper in the oven. To be right for sponge cake, the heat should turn this paper a moderate brown in 4 minutes. The time for baking depends, of course, on the size of the cake, but usually more time is required than for butter cake.
In putting the cake into the oven, set it on the lower rack, as here the mixture will be in a position to come up with the heat of the oven, which, as is known, has a general tendency to rise. If it is placed on the top rack where the heated air is necessarily passing down toward the outside walls because of the circulation that is established, there will be a certain amount of pressure on top of the cake which will prevent it from rising. Allow the cake to remain on the lower rack until it has risen to its fullest extent, and then, if necessary, remove it to the top rack for browning.
43. Several tests to determine whether sponge cake is ready to remove from the oven can be applied. One of these consists in observing the cake in the pan. After it has risen as much as it will rise, a small amount of shrinkage will, as shown in Fig. 8, loosen the cake from the sides of the pan. Another test, which is known as the finger test, consists in making a depression in the center of the cake. If the cake is baked sufficiently, it will spring back to fill the depression, but if it is not done, the depression will remain.
44. REMOVING SPONGE CAKE FROM PAN.--When sponge cake is taken from the oven, it requires different treatment from that of butter cake. Instead of removing it from the pan immediately, turn it upside down on a cooler to sweat, as shown in Fig. 9. Allow it to remain in this way until it has shrunken sufficiently from the pan, and then lift off the pan. If necessary, the cake may become completely cold before the pan is taken from it. Close adherence to these directions will prevent any trouble that may arise in removing sponge cake from the pan.