IMO about acid if it is not found at a natural source it would require a Alchemist to create. So as people said above it should be treated as a "magical" potion. For the effect I would require the PC or PC's to bring me the GM info about the acid and on what it could do, how it is made and natural sources. This takes the pressure off me as the GM to find stuff out and gives me some time to read the info and look at the rules. Also it is nice to have the players do a little work outside the game in stead of me the GM doing all the game work.
There are natural sources acids and bases but often they are in small quantities and have to be gathered or milked like venom would be.
BTW, there are also acid crits in Shadow World Master Atlas and may be in the downloads section as extra tables PDF.
MDC