It's a problem Sword, you were able to ask that question if it occurred to you. That problem is posed in a 1930's magic magazine and was posted as written. Several answers were returned the following month and the only one that worked was the sprinkling of salt.
I've a large collection of very old conjuring books and they are full of this stuff, most of which I've tried.
Here's a snippet from a book from 1873, the subject of which I'll admit to not having tried out yet. If any of our members are brave enough, let us all know how it goes...How times have changed.