Although ancestors of the Irish had likely been baking unleavened breads as early as 4000 B.C., the first record of risen breads dates from the seventh century. Back then, barm (yeast from fermenting malt) and sourdough were common leaveners, but Ireland's wheat, with its unpredictable gluten content, didn't always respond fully to them. It was not until 1790, when French chemist Nicolas Leblanc discovered an easy, inexpensive way to make sodium carbonate—essential in the production of baking soda—that people were given a more reliable option. When combined with an acidic liquid (like buttermilk), baking soda—which was convenient, cheap, and easy to store—created gases that caused dough to rise. Not only that; it also reacted well with Ireland's wheat. The Irish soon began using baking soda in their doughs—and from then on, any bread made with baking soda and sour milk or buttermilk became known as soda bread.