Make sure you inspect thebook on the "Alchemy" shelf in the café.
This one easily missed detail, (which might not be available until after you trigger a distant related puzzle,) can trap you with nothing to do and no clear indication of how to progress if you solved said puzzle without getting the extra clues.

(*sigh. I'm trying to maintain a positive attitude, but this requirement for plot advancement could trap a proud person playing on "Master" difficulty who brute forced a puzzle because they unintentionally knew "too much" into wasting time and pushing past the two hour refund limit...)