You can eat a small amount of arsenic without dying, so that’s been tested. (Plus, death from arsenic poisoning isn’t instant, so you could ask someone.) IIRC, the claims about the smell of hydrogen cyanide come from one person that survived inhaling a very small amount accidentally.
No, it’s cyanide. Bitter almond, specifically. Arsenic has no flavor to humans.
How do you know?
You can eat a small amount of arsenic without dying, so that’s been tested. (Plus, death from arsenic poisoning isn’t instant, so you could ask someone.) IIRC, the claims about the smell of hydrogen cyanide come from one person that survived inhaling a very small amount accidentally.
Specifically HCN. I don’t think the salts smell, but I’m not positive on that. But they are also toxic.