The Book of Household Management by Mrs. Beeton

373. The browning for soups (_see_ No. 108) answers equally well for

sauces and gravies, when it is absolutely necessary to colour them in this manner; but where they can be made to look brown by using ketchup, wine, browned flour, tomatoes, or any colour sauce, it is far preferable. As, however, in cooking, so much depends on appearance, perhaps it would be as well for the inexperienced cook to use the artificial means (No. 108). When no browning is at hand, and you wish to heighten the colour of your gravy, dissolve a lump of sugar in an iron spoon over a sharp fire; when it is in a liquid state, drop it into the sauce or gravy quite hot. Care, however, must be taken not to put in too much, as it would impart a very disagreeable flavour. BEURRE NOIR, or BROWNED BUTTER (a French Sauce).