Preheat oven to 325 degrees. Lightly grease a 9x5" loaf pan or a 6-cup souffle dish.
With an electric mixer, beat butter and sugar until fluffy. Separate egg yolks and whites. Add yolks to butter mixture and beat well. Add lemon juice, salt and flour; beat well. Add milk; stir until well blended.
Beat egg whites until stiff. Gently fold into lemon mixture. Pour batter into the prepared pan. Bake for 50 minutes, covering with foil for the last 10 minutes if the top gets too brown. Serve warm or chilled with berries.