Mashed Potatoes.
Whip light with a fork until dry and mealy; then beat in butter, milk, and salt.
Horseradish Sauce.
Heat and strain a cupful of the beef pot-liquor. Stir into it a tablespoonful of butter, rolled in a teaspoonful of flour. When it thickens, take from the fire and whip in the whisked white of an egg; then two tablespoonfuls of grated horseradish, and the juice of a lemon. Set in boiling water until wanted.