Cream of Tartar Tips…
Cream of tartar is a fine white powder that can be used in many different dishes. It is a byproduct of the wine-making process as the powder forms inside wine barrels during fermentation. It comes from tartaric acid, a naturally occurring substance in grapes and some other tart fruits that in the principle acid in wine-making.
It is an acid and it is often used as a major component in baking powder, combined with baking soda to react when the mixture is moistened to ensure that your baked goods will rise well. While it is an acid the cream of tartar and the baking soda will not react when dry, so the entire reaction happens in the mixing bowl and the oven. Cream of tartar is used as a stabilizing agent and is added to beaten egg whites in meringue to increase their stability and volume.
There is no exact substitute, but sometimes vinegar can be used.You could use it for meringue or when a baking recipe calls for both cream of tartar and baking powder.