, it is believed that if a conjurer
boils a black cat
Okay, excuse me for a moment while I gag.
...it is believed that if a conjurer boils a black cat alive, one of its bones will, when placed in the conjurer's mouth under the tongue, make him or her invisible. Or it can be anointed with Van Van Oil and carried in a mojo bag to bring back a lost lover.
Ariel Hawksquill does the invisibility trick in the novel Little, Big by John Crowley. I urge you, however, in the STRONGEST TERMS IMAGINABLE, not to boil, bake, fry, or otherwise harm a cat for any reason.