Troth Glenbeard was a dwarf with a mission. And that was destruction.
From there, things happened. And the Irondeeps got a Subterranean-Transport-System-That-Moves-Things-Around-Faster-Than-Equine-Means (aka, in modern-speak, a subway).
Poison can only ever be the tool of a murderer - as such, alchemists are tightly regulated by the Crown, and anyone found in posession of an unknown substance is forced to taste it themselves.