I've been storing up some baker's ammonia ("ammonium carbonate", really a fearful mixture of substances including ammonium carbonate, ammonium bicarbonate, ammonium carbamate, and other things) for ages now and I should try using it in something. it is the only chemical leavening agent that leaves zero residue after baking and I've wondered whether substituting it for baking powder might improve the taste of certain things, like American-style biscuits