Yup.
@ Montag: Don't take things to extremes. No matter how much discussion about it there is, Toady is not going to add in muskets. He has said that time and again.
As for the acids and Pitchblende catapults of which you speak, you have clearly not taken much chemistry. For one thing, uranium doesn't make A-bombs, plutionium does (which is made in uranium reactors, in small amounts. Pitchblende is also only part uranium oxide). Also, there are a number of factors that affect how corrosive an acid (sulfuric acid) or base (lye aka NaOH) depends on type, whether it dissociates completely or not, the concentration of the solution, and possibly other things I can't think of at the moment. Now, all that is too complex for 1400 knowledge or for gameplay, so in game different acids would have varying strengths and uses.
As for mercury, well, it was a popular substance in alchemy, which fits right in DF.
So chemistry = yes. Just because we have some crude explosives doesn't mean we'll get rapid fire guns. Oh, and about that; Rapid fire crossbows are a bug in the current game. Firing rate in game is something that should be completely ignored when considering the addition of new ranged weapons.