Ottawa Citizen - There's more to dry ice than a mystical fog

McGill Chemistry professor Joe Schwarcz

"Double, double toil and trouble, fire burn, and cauldron bubble!" But how do you make that cauldron bubble on stage? That's what the stage manager of a local production of Macbeth wanted to know. Wasn't too hard to answer that one. It just takes a little chemical witchcraft in the form of dry ice!