James Randi and The Psychic Chemist

I saw this one a long time ago and have only just managed to find it again. I think the clip ends before any explanation of how it was done comes up.

It's easy. The initial liquid is a weak alkali and the coloured liquid is a pH indicator. The high stirring speed is essential because all that's needed to change the pH from alkali to acid is carbonic acid. Which is what you get when you dissolve carbon dioxide in water. Which is what happens when you breathe into rapidly-stirred water. The rapid stirring means his breath dissolves faster.

All he's doing is breathing into the water. A drop of alkali changes it back, and all he needs do is breathe into it again.

This is one of those fakes that makes life very difficult for me and others, and I despise him for it.

The scientist, if she is one, is either in on the act or is a completely useless idiot. I suspect the former.