Natural gas does not have any odor. In order to detect a gas leak, some gas companies add a chemical that smells similar like rotten eggs.

The first commercial chewing gum was sold in 1848 by John B. Curtis, who also made the gum. He called the gum "State of Maine Pure Spruce Gum."

The world's first underground was the London Underground in1863. It has 275 stations and 253 miles of track.

AMAZING FACTS