It's hard to believe, but this is something that was sold as a means of detecting radioactive radiation

Well, again Radioactive Incidents. Well, there is, in principle, is not radioactive, of course, but also in the subject. Look. 

This cute set was produced in the mid-1950s by the Davis Detroit company of Detroit.

Inside the box is written: "This is the oldest form of atomic radiation detection: sensitized photographic film of the highest quality. It was first discovered by Antoine Becquerel in 1896. Now you can understand that radioactive fallout is pouring on you and experience the unheard-of pleasure of discovering uranium in random places."

And in principle, so it all is. The process there is not too fast and simple, but, in General, everyone will cope. And find out if he was under radioactive fallout or not. Ah later 24 hours truth. But also not bad.