Quick bread leavening agents include a weak base, such as baking soda (sodium bicarbonate) plus a weak acid, such as cream of tartar, lemon juice, or cultured buttermilk, to create an acid–base reaction that releases carbon dioxide. (Quick bread leavened specifically with baking soda is often called "soda bread".) Baking powder contains both an acid and a base in dry powdered form, and simply needs a liquid medium in which to react. Other alternative leavening agents are egg whites mechanically beaten to form stiff peaks, as in the case of many waffle recipes, or steam, in the case of cream puffs. Nevertheless,
Sodium bicarbonate amounts of product are further obtained by solution mining, pumping heated water through previously mined nahcolite beds and reconstituting the dissolved nahcolite above ground through a natural cooling crystallization process. Currently, only Genesis Alkali (formerly Tronox, formerly FMC) in the Green River Wyoming basin has successfully commercially solution mined the product. Sodium bicarbonate, as "bicarbonate of soda", was a frequent source of punch lines for Groucho Marx in Marx brothers movies. In "Duck Soup", Marx plays the leader of a nation at war. In one scene, he receives a message from the battlefield that his general is reporting a gas