NOTE: REDUPLOADED DUE TO AN ERROR IN TERMINOLOGY. Warning: H2S is EXTREMELY toxic. Do NOT do this indoors and avoid using H2S if you can. In this video, I generate hydrogen sulfide using hydrochloric acid (HCl) and iron sulfide (FeS). I bubble the gas through a saturated solution of copper sulfate to limit the amount of H2S released into the environment and to demonstrate it's (old) use as an analytical chemistry technique.