Put about a gallon of stock, No. 1, or brown gravy, No. 3, into a stewpan on the fire; and when it is warm, stir into this three-quarters of a pound of brown thickening, No. 9.
Continue stirring the sauce on the fire until it begins to boil, and then remove it to the side, there to remain very gently simmering for an hour, with the lid on the stewpan; by that time all the butter of which the thickening is composed will have risen to the surface; this, together with the skum, must be removed; and after allowing the sauce to boil very gently by the side of the stove for another quarter of an hour, continuously removing tho skum as it rises, strain the sauce into a basin for use, as will be hereafter directed.