Add 1 drop of blue food coloring to the cold water and gently mix. Ask your adult partner to add two tablespoons of hot tap water to a separate cup. Add 1 drop of red food coloring to the hot water ...

Why are there separate taps for hot ... cold were on," said Mr Wellman. "When mixer taps came into vogue there was still a requirement to make sure water didn't mix until it came out of the tap ...