Clyde Baker's "Modern Gunsmithing" (1933) has a good deal of information about cyanide hardening. It also contains caveats about the dangers of using the stuff- a dog died instantly from a drop in his eye and a photo engraver took a few steps before dying in midstep from using a glass which had a few drops in it. I'd be leary about mixing up a bucket of the stuff and cooking it on the stove. Unless my ex-wife's lawyer was coming to dinner.

Cary