This section is from the book "Practical Cooking And Serving", by Janet McKenzie Hill. Also available from Amazon: Practical Cooking and Serving: A Complete Manual of How to Select, Prepare, and Serve Food [1919].
All simple sauces are produced from roux, white, or blond, or brown, salt, and pepper, and liquid, either cream, milk, water or stock.
Roux, used to give body to sauce, is made with equal weights of flour and butter, or with half the weight of butter in flour cooked together. By measure, it is half a cup, each, of butter and flour to a quart of liquid; two level tablespoonfuls, each, of butter and flour to one cup of liquid. For a white sauce, melt the butter in a small, smooth and perfectly clean saucepan; when it bubbles, add the flour with salt and pepper and cook and stir until the mixture takes on a yellow appearance, from three to five minutes. When a brown sauce is desired, use clarified butter, let cook until it begins to brown, add the flour, continue the cooking with constant stirring upon the top of the range - or it may be done with occasional stirring by setting the saucepan in the oven - until the mixture has acquired a russet brown or reddish color; this is roux proper, a white roux being one of the contradictions in cookery. When this has been done, let the roux cool by drawing it to a cooler place on the range, add the liquid gradually and stir constantly. When all of the liquid has been added bring the sauce to boil vigorously, then remove to a cooler place and let simmer five minutes. Unless it be time to serve, let stand in hot water, covering it meanwhile to avoid the formation of film on the surface. If, after standing, the butter separates from the sauce giving an oily appearance, add a tablespoonful of cold liquid and stir constantly, until the mixture boils again. If a sauce be thicker than desired, add more liquid; if too thin, make a roux, let cool, and gradually add the sauce to it.
2 tablespoonfuls of butter (1 ounce). 1 cup of milk or white stock. 2 tablespoonfuls of flour (1/2 ounce). 1/4 a teaspoonful of salt. 1/4 teaspoonful of white pepper.
Use cream instead of milk and from one to two tablespoonfuls of flour, according to the thickness of the cream; otherwise, the same as white sauce.
(for croquettes and similar mixtures)
Three tablespoonfuls of butter, one third a cup of flour, one cup of milk, or white stock, or cream and white stock combined. Use the same quantity of condiments and prepare as white sauce.
Same as white sauce, with white stock, preferably chicken flavored with onion, celery, carrot, and a bouquet, as the liquid.
To a pint of velouté sauce add one fourth a cup of mushroom liquor, reduced by simmering to about a tablespoonful, mushrooms cut in halves, or chopped if desired, and the yolks of two eggs, beaten and mixed with one tablespoonful of creamed butter. Before adding the yolks and butter, remove the saucepan from the fire, let cool a moment or two, then add a little of the sauce to the eggs; mix thoroughly, add more sauce, mix and return to the saucepan and stir over the fire a few moments without boiling.
 
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