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].
1/3 cup of butter. 1/4 teaspoonful of salt. 2 tablespoonfuls of flour. 1/4 teaspoonful of pepper. 1 cup of water.
Use half the butter with the flour in making the roux: when ready to serve, beat in the rest of the butter, a small piece at a time. As in making all sauces thickened with roux, cook the flour thoroughly before adding any of the liquid. The feature of this sauce is the addition of the butter, little by little, after the completion of the cooking.
(for fish)
To a pint of butter sauce add from one fourth to one half cup of chopped cucumber pickles.
To a pint of butter sauce add from one fourth to half cup of capers.
(for boiled fish)
To a pint of butter sauce add two or three hard-boiled eggs cut in one fourth inch slices, or chopped rather coarsely.
(for fish)
Pound the flesh of four anchovies with two tablespoonfuls of butter in a mortar; stir into a cup of butter sauce, pass through a sieve, reheat and add the juice of half a lemon.
(For Baked Fish, Especially Shad)
To a pint of butter sauce add the juice of half a lemon and half a cup of fine-chopped cooked spinach; strain a part of the sauce over the fish and serve the rest in a sauce boat. Do not strain out the spinach; use a sieve and pass the spinach through it. The beaten yolks of two eggs may be added with the last of the butter.
 
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