Is composed of soda and cream of tartar in definite, correct proportions, mixed with small quantity of dry material (flour or corn-starch) to keep action from taking place. If found to contain alum or ammonia, it is impure. In using baking powder, allow two teaspoons baking powder to each cup of flour, when eggs are not used; to egg mixtures allow one and one-half teaspoons baking powder. When a recipe calls for soda and cream of tartar, in substituting baking powder use double amount of cream of tartar given.
These rules apply to the various soda and cream of tartar baking powders on the market. Horsford’s Baking Powder, the only mineral one, requires one-third less than others.
Soda and cream of tartar, or baking powder mixtures, are made light by liberation of gas in mixture; the gas in soda is set free by the acid in cream of tartar; in order to accomplish this, moisture and heat are both required. As soon as moisture is added to baking powder mixtures, the gas will begin to escape; hence the necessity of baking as soon as possible. If baking powder only is used for raising, put mixture to be cooked in a hot oven.