Royal Baking Powder - cooking recipe

Ingredients

2 tablespoons cream of tartar
1 tablespoon baking soda
1 tablespoon cornstarch

Preparation

Mix three ingredients together thoroughly.
Use 1 teaspoon of this mixture for each teaspoon of Royal or single-acting baking powder called for in a recipe.
Do NOT use this mixture in recipes calling for double-acting baking powder.
Store leftover mixture in a covered container.