Cream butter; gradually add sugar, beating well. Add eggs, one at a time, beating well after each addition. Combine 2 1/2 cups flour, cream of tartar, and soda; add to creamed mixture alternately with milk, beginning and ending with flour mixture. Dredge fruit in remaining flour; stir into batter.
Pour baiter into a well greased 10-inch tube pan. Bake at 375° for 55 to 60 minutes or until cake tests done. Cool in pan 10 minutes; remove from pan, and let cool completely on a wire rack Yield: one 10- inch cake.