I'm fairly sure mercury wouldn't work
For one thing, it's 13 times denser than water, so even adding a small amount to someone's glass would make it feel weirdly heavy. Secondly, because it's so dense and not miscible with water it would just sit in the bottom of the glass until whoever was drinking would spot it. I don't honestly think they'd miss it. Someone tried this with oranges once, a while ago - they injected the oranges with mercury, but when people peeled the oranges the mercury just fell out.
(Petite chien is going to do science to it, Wed 8 Feb 2012, 17:45, 1 reply)

I'm glad it wasn't just me
thinking along these lines.
( Enzyme is powered by sunlight, Wed 8 Feb 2012, 19:56, closed)