Wash and scrape carrots; cut off the darker part, and chop fine or force through meat-chopper. Cook with one-half the butter fifteen minutes. Add stock and mace, and cook slowly forty-five minutes. Strain, and rub carrots through sieve. Melt remaining butter, add flour, and pour on gradually hot stock. If a more delicate soup is desired, substitute White Stock and cream for Brown Stock, using one quart stock and one cup cream or milk.