Melt the butter in the warm milk, adding the soda; and stir in the sugar by degrees. Then sift the flour into a pan; make a hole in the middle; pour in the milk, etc., and mix it with the flour into a dough. Put it on your paste-board, and knead it long and hard till it becomes very light. Roll it out into a sheet half an inch thick. Cut it into little round cakes with the top of a wine glass, or with a tin cutter of that size; prick the tops; lay them on tins sprinkled with flour, or in shallow iron pans; and bake them of a light brown in a quick oven; they will be done in a few minutes. These biscuits keep very well.