Perfect Old-Fashioned Sponge Cake

From 1910:

Weight of the eggs in sugar and half the weight in flour.
Separate the yolks and whites of the eggs and, as no baking powder is used, they must be beaten very light. After beating the yolks and sugar until they froth, and the whites until they stand alone, blend by putting in a little flour and then a little white, alternately, until all is in the bowl.
Rosewater is the orthodox flavoring for sponge cake, but of course, any liked maybe used.
Lastly squeeze in the juice of a lemon, beat quickly and put to bake. Sponge is usually baked in sheets, takes about twenty minutes, but if the whole is baked in a loaf, it will take about forty minutes.