Cream of Tartar
OK, here's one of those weird things we/I take for granted. I know cream of tartar is used in desserts (???), but I've not used it in this millennium. What is it, where does it come from, will it be available if folks want it in the Long Descent. I had no idea it was a precipitate from fresh grape juice and a by-product of wine-making. And it's also used as a household cleaner.