The Epicure's Almanac or Diary of Good Living
January 3rd : ICEING FOR CAKES
Reduce a pound of the best loaf sugar to a very fine powder in a mortar; beat up the white of an egg ; add this to the sugar, mixing it well, and then squeeze in the juice of a lemon, mixing that also thoroughly. With the blade of a knife spread this smoothly over the top of the cake whilst hot.