For some reason lost in the fog of time, baking powder had usually been packaged in cylindrical cans with bright graphics in eye-catching red, yellow and black. Baking powder is, of course, a leavening agent used in the making of bread and other foods. It is a chemical leavening agent, which generates carbon dioxide gas bubbles following the mixing together of a base, usually sodium bicarbonate, and an acid (one or more acid salts), in the presence of water.