Soda Biscuits
Take 1 lb. of flour, and mix it with milk enough to make a stiff dough; dissolve in a little milk 1 tsp. carbonate of soda; add this to the paste with a teaspoon of salt. Work it well together and roll it out thin; cut into round biscuits, and bake them in a moderate oven at approximately 350 degrees. The yolk of an egg is sometimes added. (Sarah J. Jale, Mrs. Hales New Cookbook 1857)