1. Beat butter or margarine with 3/4 cup of the sugar until fluffy in medium-size bowl with electric mixer at high speed. Beat in egg, vanilla, lemon extract and milk.
2. Sift in flour, baking powder, salt and baking soda, a little at a time, blending after each addition; chill dough several hours, or until firm.
3. Form into marble-size balls (about 1 teaspoonful for each) by rolling lightly between palms of hands. Coat balls by rolling in a mixture of remaining 1/2 cup sugar and lemon rind; carefully place, 2 inches apart, on cpokie sheets.
4!. Bake in moderate oven (350°) 8 rninutes, or until tops are crackled and edges are lightly browned; cool completely on wire racks.