In a mixing bowl, beat butter and sugar until light and fluffy. Beat in eggs, one at a time, until batter is smooth. Add vanilla, anise, lemon rind and juice, flour, baking powder and salt. Beat just until thoroughly blended. Mix in walnuts. Cover and chill dough at least 4 hours. Divide dough into several portions. On a lightly floured board, roll dough into logs about 1 1/2 inches in diameter and the length of the baking sheet. Bake logs, spaced 2 to 3 inches apart, in a pre-heated 325-degree oven for 30 minutes, or until golden and firm to the touch. Remove from oven and let cool for 10 minutes. Lower oven temperature to 300-degrees. Cut logs in 3/4 inch thick slices. Place slices, cut side down, on baking sheets. Bake for 15 minutes, until biscotti are dry. Cool on wire racks. May be stored in an airtight container for several weeks. Makes 8 dozen. ** Recipe taken from Chicago-Sun Times Food section, 11/22/92. Posted to MM-Recipes Digest V5 #030 by "Robert Ellis" on Jan 29, 1998