I remember this from the 70's, the supposed ability to photograph the invisible soul or aura that surrounds all living (and many dead or inanimate) things. So - imagine my excitement when I turned this up in a thrift shop - bargain priced at a mere $125.
Of course, it doesn't do that at all, although there's enough of a market I'm sure that you could do pretty well with it.
That said, I'm pretty sure it would be easy enough to write a computer program that would digitally create an aura effect and spare you the handling of film and the other inconveniences. Still, a great prop for any ghostbusters or psychic researchers...