I actually think Chloroform fits the bill, since commercial use and production began by the 1850's (It had been synthesized twenty years before and used mostly as a reagent/neat trick at parties) Plus its use as an aesthetic is notoriously risky, here's a quick snippit.

[hider=Snip]The anesthetic use of chloroform has been discontinued because it caused deaths due to respiratory and cardiac arrhythmias and failure. Following chloroform-induced anesthesia, some patients suffered nausea, vomiting, prostration, jaundice, and coma due to hepatic dysfunction. At autopsy, liver necrosis and degeneration have been observed.[6]

Chloroform has induced liver tumors in mice and kidney tumors in mice and rats.[6] The hepatotoxicity and nephrotoxicity of chloroform is thought to be due largely to phosgene.[/hider]

That said I'm not so sure a chloroform soaked rag would be much use against hunters or beasts....