ALUM

a salt composed of the combined sulphates of Potassium and Aluminum. It crystallizes in cubes and eight-sided forms, and has a sweetish astringent taste. It is sometimes employed by bakers to whiten their bread. That used in Baking Powders is Burnt Alum-a white spongy substance produced by heating alum until it melts and then driving off all the moisture by additional roasting. Its employment in baking powders has been much abused by parties interested in other preparations, but if completely neutralized it is harmless. The taste test is a poor one, as no raw baking powder has a pleasant flavor, and an overdose of cream of tartar would be about as bad as one of burnt alum!