fyi, I set up that demonstration myself in lab over the weekend. it's pretty cool. you want about equal parts acid and alcohol, but not too much of either - I used about 2 mL of each, and that was PLENTY. reaction continued for easily 10 minutes. my KMnO4 was finely ground, but the bigger crystals worked better - one trial actually bubbled over, though, so don't go too big on crystal size.