Cream together sugar and butter, add the egg yolks one at time; beat well after each addition. Blend in vanilla, lemon juice and sour cream.
Into a separate bowl, sift sifted flour, salt, and soda. Add sifted dry ingredients to batter; beat well. In a separate bowl, beat the egg whites until stiff peaks form.
Fold egg whites into the cake batter. Pour into a greased and floured tube pan and bake at 300° for about 1-1/2 hours or until cake tests done.