Hi Robin, welcome to the site!
Re cream of tartar: I found this definition on the web: white crystalline powder. Chemically it is potassium hydrogen tartrate, KC 4
, the acidic potassium salt of tartaric acid
. It is used as the leavening agent in baking powders. An impure form, called tartar or argol, forms naturally during the fermentation of grape juice into wine and crystallizes in the wine casks.
You can find it in the baking aisle, probably somewhere close to the nutmeg & cinnamon.