"It is an invisible gas," she said. "It has a powerful and unpleasant smell, and it burns with a bright flame.""You should have been with us in school," said Fred. "Teacher showed us another property of this coal-gas. He had a soda-water bottle, filled with a mixture of air and coal-gas.""Oh yes," said Norah, "I remember. When thecork is pulled out and the light is brought near, the gas explodes with a great bang. You told me about it when we were talking about coal.""So I did," said Fred. "I am glad you remember all about it. Teacher told us that sometimes people are careless, and leave one of the gas-burners turned on, so that the gas escapes into the room. Then wehave all the materials ready for an explosion on a terrible scale. All that is wanted is a light.
"You must never take a light into a room if you can smell gas. You are quite safe without a light, no matter how much gas has escaped.
"Go in, open the doors and windows, and the gas will soon pass away out of the room into the open air, and fresh air will take its place. Then, and not till then, will it be safe to get a light, and find out where the gas is escaping.""You remember the fire-damp in the mine," said Willie.
