Old-Fashioned Sponge Cake Recipe From the White House 1913

This old-fashioned recipe is taken from "The White House Cook Book" 
by Hugo Ziemann, Steward of the White House, and Mrs. F. L. Gillette, 
a celebrated 19th-century cookbook author, published by 
The Saalfield Publishing Company, New York, in 1913.

Two cups of sifted white sugar, two cups of flour measured before sifting, ten eggs, separated. 
Stir the yolks and sugar together until perfectly light; add a pinch of salt; 
beat the whites of the eggs to a very stiff froth and add them with the flour, after beating together lightly; 
flavor with lemon.

Bake in a moderate oven about forty-five minutes. 
Baking powder is an improvement to this cake, using two large teaspoonfuls.