If you or someone you know is into old (actually very old) recipes, odds are you’ve seen this listed as an ingredient here and there. Pearlash is refined potassium carbonate, an alkaline salt found in wood ashes that also goes by the name potash. Potash was used for a lot of things back in the 1700s and 1800s, especially glassmaking. These days we mostly know it as a fertilizer, but once upon a time it was used to leaven things like corn cakes since it makes bubbles when it gets wet. Given that potash was made from wood ash, its effect on the flavor of corn cakes was as you might expect, but hey, at least the texture was lighter.