Some recipes require self-rising flour. Not all kitchens have this on hand. In a perfect world, we plan ahead and have all the ingredients or at least have time to shop for them. Unfortunately, the modern world limits time and good planning. Ironically, self-rising flour should save us time. It contains raising agents such as baking powder that we would otherwise have to measure and put in separately. However, if your kitchen does not have self-rising flour or baking powder, adding baking soda can do the trick.
Place the required amount of flour in a bowl.
For each cup of flour, add 1 tsp of cream of tartar and 1/2 tsp of baking soda. Mix well.
Add the flour mixture to a sifter and sift together three to four times into a mixing bowl.
Mix together 6 tsp of baking soda and 8 tsp of cream of tartar in a bowl.
Place in an airtight jar and shake to mix thoroughly. Use as a replacement for baking powder.
When you are ready to use the mixture, place 6 cups of flour, 1 tbsp of salt and 3 tbsp of the baking soda/cream of tartar mixture in a bowl and stir to combine.
Place the flour mixture in a sifter and sift together three to four times and proceed with your recipe.
Baking powder cannot substitute for baking soda without changing the recipe to reduce acidic ingredients.
Measurement are approximate. For example, According to Mamta's Kitchen, increases in the fat content of a recipe, together with more eggs, would require less baking soda.