Potash alum, also known as potassium aluminum sulfate, is an inorganic compound with the chemical formula KAl(SOâ‚„)₂·12Hâ‚‚O. It is a hydrated double salt that consists of aluminum, potassium, sulfur, and oxygen. The compound forms large, colorless to white crystals and is highly soluble in water. Chemical Properties of Potash Alum …