The possibility of chemical weapons of a sort during the ACW?

First, one must stipulate that only the North had anything close to the resources that would have allowed even crude chemical weapons. What I'm thinking of is perhaps glass grenades, not unlike fire grenades, but filled with something like sulfuric acid (available in commercial quantities at the time, I believe) or white phosphorus in kerosene. Those glass grenades would have to have been launched by something resembling a 19th century trebuchet, which probably wouldn't have been too problematic, given the close ranges at which troops fought in the 1860s.

So: suppose the defenders at (say) Gettysburg, particularly Pickett's Charge, had a couple of trebuchet-like machines and a stockpile of glass grenades filled with sulfuric acid? How might that have affected the outcome of the day--and would there have been wild rumors floating in Confederate ranks thereafter of a particularly horrific Union weapon?

There were projects on the subject, both from the South and the North. The Confederacy tried even (thankfully without success) biological warfare (just smallpox ).

I cannot visualize any such weapon which would outrange the small arms and cannon they already had. Meaning, the chemical weapons would be vulnerable to being "set off" among their would-be users by incoming bullets and shells before they could be used.

I am not sure they could get the right degree of "breakability" in any "glass grenade" weapon - if a thrown grenade falls into high grass or soft ground, it could be picked up intact by the intended target. I suppose said target could also just catch it and throw it back, but that seems a bit over the top...

I suppose somebody could design a device for launching "glass grenades" (we were sending water balloons a few hundred feet in college), but there still seem to be a lot of ways for things to go wrong (we regularly had balloons break in the launcher).

The idea of trebuchets and glass grenades seems overly comlicated. Most of the OTL plans simply involved filling glass or iron shells with material and firing them from a normal canon or mortar. From memory, the best proposals were filling shells (of either glass or iron, apparently either would have worked) with cyanide cacodyl or hydrogen sulfide. The shell didn't have a burstign charge, it was just supposed to break open when it hit.

I've gone and pulled a journal article on this subject and I'll post what I find in it.

OK: I went the purely mechanical route because (a) I know so-called fire grenades, commonly filled with carbon tetrachloride eek were in use at about that time, and it would have been no problem to substitute sulfuric acid as the contents, and (b) I wasn't aware glass shells could be made and fired from artillery.

Hydrogen sulfide wouldn't be terribly effective as a chemical weapon, by the way: it's marginally heavier than air, that's true, but it disperses fairly readily and you'd need a lot of shells filled with that stuff to have much effect. A light breeze would dilute it pretty rapidly, and the stink would warn would-be victims instantly (true, the olfactory nerves become numb, so to speak, after prolonged exposure, but the smell would likely be enough on a battlefield to serve as a warning). On the other hand, tetramethyldiarsine has most of the requirements for a chemical weapon: a liquid with a fairly high vapor pressure at ambient temperature, persistence, and rapid effects. Probably it wasn't all that easy to make in commercial quantities in the 19th century, but at least it was known.

I chose sulfuric acid since it's fairly easy and cheap to make, and the diluted stuff (say, ~20% by weight, roughly) is incredibly hygroscopic--and the heat of dilution is violently exothermic. In fact, it's sufficient such that sulfuric acid applied to paper or wood can cause it to ignite. Imagine what that might do to a field of dry grass...same generally goes for white phosphorus.