This is the Espagnole sauce, having reached the limit of perfection by final despumation. It is obtained by reducing one quart of Espagnole and one quart of first-class brown stock until its volume is reduced to nine-tenths of a quart, it is then put through a strainer into a bain-marie of convenient dimensions, and it is finished, away from the fire, with one-tenth of a quart of excellent sherry. Cover the bain-marie, or slightly butter the top to avoid the formation of a skin. This sauce is the base of all the smaller brown sauces.