Beat egg yolks until well blended. Sift together flour, soda and salt. Stir in buttermilk and egg yolks. Add butter and beat until smooth.
Beat egg whites with an electric mixer until stiff but not dry. Fold into batter gently.
Heat a lightly greased griddle or large nonstick skillet over medium heat. Test heat by dropping a small amount of batter into the pan. Once pan is hot, drop batter by spoonfuls onto pan and cook until pancakes are brown on the bottom and are starting to dry on top. Turn and brown the other side. Keep warm while cooking the remaining pancakes.