And the answer: baking soda.
Sodium bicarbonate is another name for baking soda. It is often used as a leavening agent for baking. When baking soda interacts with an acid, the reaction results in the creation of carbon dioxide, which lifts baked goods while they’re in the oven.
The history of baking soda lies mixed within a history of impatient bakers (or, really, innovative bakers). Around the 1830s, bakers discovered that they could create a quick chemical reaction to avoid the time commitment of waiting for bread to rise on its own. Without agents such as baking soda or baking powder, bakers would let the dough sit out so that the yeast from the air could move in. These yeasts digest the sugar in the flour and produce CO2 in a natural process called fermentation. However, all things said and done, this process took at least a couple hours, if not overnight.
Enter: baking soda. This chemical leavening agent is made from soda ash, which at the time came from the ashes of sodium-rich marine plants such as seaweed or through a reaction between table salt and other chemicals. Interestingly, the baking soda on grocery store shelves today is made from the same compound we've been using for almost two centuries. Either the baking soda is created in the mining process, or it is chemically manufactured. To chemically manufacture baking soda, carbon dioxide and ammonia are passed into a concentrated solution of sodium chloride. While this method is effective, it can also leave behind harmful solid waste products.
The other method of acquiring baking soda is a historic process based in Wyoming mines. By mining and processing Trona Ore, scientists were able to produce baking soda from natural sources.
Learn more about the history and uses of baking soda here.