Add salt and baking powder to flour. Sift twice and set aside. Cream together butter, shortening, and sugar. Mix until smooth. Add eggs and milk. While still mixing, slowly add flour. When smooth, add vanilla and lemon extracts. Continue mixing until completely smooth and there are no sugar granules. Pour into greased and floured bunt pan (about 12x9). Bake in pre-heated oven at 325 degrees for about 90 minutes. When top is springy, remove and let set until sides come away from the pan. Turn out on cooling rack and slowly remove pan.