Vanilla Sour Cream Pound Cake

3 cups granulated sugar
1 cup butter
6 eggs, separated
2 teaspoons vanilla
1 cup sour cream
3 cups all-purpose flour, sift before measuring
1/4 teaspoon baking soda
1/4 teaspoon salt

Cream together sugar and butter, add the egg yolks one at time; beat well after each addition. Blend in vanilla 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.