invented to keep out the cold
The next truly important thing she has to do is get to that meeting with Julio and Anton, where they can work out what the books are worth and how they're splitting the money. She did only say she wouldn't take a share of anything she couldn't use, after all, and money is very usable. In the meantime, it would be foolish to dive into another dangerous adventure before spending that. There are surely things she could do to improve her chance of survival if she goes out again, and dying because she couldn't wait a week would just be dumb. In the meantime, then, she should try to figure out this thing with Acid Splash.
On Moonday, she finds herself some odd jobs here and there, things which might be a bit dangerous without the ability to knock most muggers unconscious but which she can handle. That brings in enough for her to get a few pinches of brimstone. When she uses them in an Acid Splash, they definitely do something! The spellform collapses around them like a normal component, and while they vanish with the spell's release, she can feel that the acid was a bit hungrier. That's the effect she wants to replicate. She tries casting it a few times, holding that feeling in her mind, but gets nowhere.
Toilday and Wealday she spends tutoring showing off her Color Spray to an Academae student who apparently kind of sucks at studenting, and couldn't figure out how to match the form of a circled spell to the diagrams even with his Detect up. Ten castings later, he's figured out how all the various bits and pieces work out, and has paid her shown his gratitude with a few shields and, more importantly, quite a bit of brimstone. She didn't ask how he got access to it. If it matters, it's better that she doesn't know.
With the brimstone in hand, her Oathday is a time to cast repeatedly, shifting by just a bit each time. She can replicate that part of the effect if she feeds the spell a bit of breath and pushes it off her hand slightly differently. If she tugs on the knot just as it's coming out, she can get that part to stabilize. If she pulls in a smidgen of the shadows from within her mouth, she can shape it into some of the fuzzy grabbiness the acid needs to replicate... As she goes on, she can use less and less brimstone for the same effect. By the end of the day, she thinks she pretty much has it, but she's out of brimstone. And she can't do it without spending a while concentrating, which is less than useful in combat.