Miss Bianca in the Salt Mines

As you may have gathered from the animated 'Rescuers' series, this is a book about mice, or more specifically about Mouse. Miss Bianca is well-represented by whichever of the Gabors it is that does her voice in the movies; she is just that kind of mouse. When traveling by air, she goes by diplomatic pouch; all her little mouse things are described quite cunningly the same way Stuart Little's are by E.B.White. She is a member on active duty of thhe Rescue Aid Society, which organization rescues children who are prematurely aged from misfortune, not developmentally delayed as in the movies. I remember Miss Bianca in the Salt Mines quite well; a little girl is stuck in a crystalline salt mine where she waits on a Duchess, whose entire china set is made of crystal. As I'm writing this I'm wondering if maybe I missed some double meanings because it sounds so implausible. The Duchess has ratty white hair which our orphan must brush with a crystal-backed brush; the Duchess has a walking stick with a huge crystal (a diamond?) on top of it with which she raps at the orphan. I guess I don't remember it quite as well as I thought. I will say that the entire Miss Bianca series is outstanding!