I assume that you mean hydrogen cyanide gas. How did you know that this
gas was what was released?
I'm asking because I've heard stories such as yours before, but when
I look up potassium ferricyanide in various references (such as Shaw's
"Overexposure") they describe potassium ferricyanide as very stable,
and that it takes combining it with hot concentrated acid to release
hydrogen cyanide gas.
Perhaps someone with a better chemistry background than I have could
comment.
Carson Graves
carson@ileaf.com