Preheat oven to 350 F. Grease a 10-inch bundt pan.
Cream the butter and gradually add the sugar, beating until light.
Beat in the egg yolks, one at a time, and the orange zest.
Sift the flour with baking powder, baking soda and salt.
Add dry ingredients alternately with the orange juice to the batter.
Beat the egg whites until stiff and fold them into the batter.
Pour batter into the prepared bundt pan.
Bake for 30-35 minutes, or until sides of cake shrink away from edges of pan and a cake tester inserted in the center comes out clean.
Cool for 10 minutes in pan, unmold onto a rack, and drizzle with Orange Glaze while warm.