Conc sulphuric acid for telling Panaeolus or Psathyrella

Dear friends.

I.have read in few different sources about the use of concentrated sulphuric acid on the spores so as to tell the difference between Panaeolus (spores remain dark) and Psathyrella (spores are bleached off).

Is this a reliable test?

Is the change rapid (few mins)?

I appreciate if u can share Yr experience with me about this subject.

Thanks 😊

Some reliable examples (worth testing!)

FloraAgaricinaNeerlandica_Vol1 (1988)

FloraAgaricinaNeerlandica_Vol6 (2005)

A.other source