A group of tourists visits a museum. The main attraction of a museum is a large diamond. After the tourists hae visited, the museum guard finds out the diamond has been stolen. The police get all the tourists who visited the exhibit and put them in a room. Unknown to them, the diamond has been covered with a solution that turns green when it comes in contact with salt. The detective who questions them tells his assistant to turn up the furnace. Why does he do this?
Solution
The sweat they will produce in the heat has salt. Since one of them obviously picked it up with his hands, the diamond will have stained the culprit’s hands and in the heat, the person’s hand will eventually sweat, giving away the culprit.
