A blacksmith wishes to cool his hot piece of steel as rapidly as possible. He has a bucket of ice-water and a bucket of oil (at room temperature). Which bucket should he dump his steel into? 

VIEW SOLUTION BELOW

THE SOLUTION

He should put the steel into the oil as the liquid will lower the temperature quicker. The water will actually boil as it touches the metal, but that gas will insulate the hot steel from the rest of the cooling water.