Used to increase and stabilize beaten egg whites in meringues and angel food cake, Cream of Tartar is a natural byproduct of making wine.  It can also be used to make baking powder. Use 1/4 tsp. per 4 egg whites and add to the egg whites while beating. To make baking powder, combine 2 tsp. Cream of Tartar, 1 tsp. baking soda and 1 tsp Cornstarch and blend well.