If you found a dead kitten in your home from your cat having them and you had no idea, and the kitten was dried out and basically mummified, what uses could you keep it for?
Cats in folklore and magic are both Saturnine and Mercurial. Cats have been used in folk magic over the years for invisibility, luck, pacts with the devil, gaining the powers of witchcraft, invincibility, and obtaining spirit sight. In superstition, black cats are often considered unlucky, attracting death and the evil eye. I’ve listed a few historical workings below for your perusal. As you can see, many many historical grimoires have uses for cats or cat body parts.Â
 From the Epistle of Rehoboam:Â
 “The herb of Mercury is the cinquefoil. Uproot it at the hour of Mercury, while reciting the proper incovation and the names. Take the flowers and the seed, wrap them in the heart of a black male or female cat, and carry them upon you. You will be invisible.”Â
 From MS Sloane 3851 is a Working To Go Invisible:Â
 “At such time as Men sow Beans. Take a Bean and but it into the heart of a black cat being ready roasted. Then bury it in a dunghill or in alio loco saturnaliter and when they be ripe carry one about thee and thou shalt be invisible.”Â
 From the Egyptian Secrets of Albertus Magnus - To See What Others Cannot See:
“Take a cat’s eye, lay it in salt water, let it remain there for three days, and then for six days into the rays of the sun, after this have it set in silver, and hang it around your neck.”Â
 From the Black Books of Elverum, For Invisibility:Â
 “Poke out the eyes of a bat and put them in your pocket. Smear yourself with bat’s blood. Then take the eye of a black cat, cook it in sweet milk. After eating drinking this, you’ll be invisible for nine hours,”Â
 Again. I am not endorsing the eating of cat’s eyes, simply presenting some folk magic/grimoire uses for cat parts.Â
 The Opuscula Cypriani lists a few variants on recipes to create a perfume for Saturday, citing the Petit Albert as the source:Â
 Perfume for Saturday or perfume of Saturn - Add seeds from black poppies, henbane, mandrake root, asbestos powder and myrrh. Make all of these elements into a powder and incorporate them with blood from a mole and the brain of a black cat, form a paste, divide it and let it dry.Â
 It abso-fucking-lutely goes without saying that I’m listing these here as inspiration and am in no way telling you to make an incense using asbestos and solanaceae. Use your good common sense. If you're interested in finding more uses for cats, I suggest picking up almost any grimoire or looking them up online. I'm sure Agrippa has a few things to say on the subject as well. Opuscula Cypriani and St. Cyprian The Sorcerer's Treasure also have many spells/rites/workings involving the usage of cats.