Did you ever think what flame is in a common wood or coal fire? It is burning gas. The heat makes the gas out of the wood or coal, and this takes fire just as the gas does that comes out of the burner when you put a light to it. Sometimes you see a little stream of gas blowing out of some part of a stick of wood, as gas blows out of a burner. It makes quite a noise as it blows. If it is not on fire, you can set fire to it just as you light the gas from a burner.
You see, then, that every fire-place, or grate, or stove is a gas factory; but the gas is burned up as fast as it is made. The gas which is made at the gas-works is made in such a way that it is not burned at the time. It is made generally by heating coal, and is kept in large reservoirs called gasometers. From them pipes branch out in the same way that they do from water-works; and through these the gas goes all about to different buildings, as water goes in aqueduct pipes; and as the water comes out when you open the faucet, so does the gas when you open the burner.
Gas from burning charcoal.
There is one gas that every one ought to know about, because many persons have been killed by it from want of this knowledge. This gas is made whenever charcoal is burned; and many deaths have occurred from it by burning charcoal in small furnaces in close rooms. This is often done to warm a room where there is no stove or fire-place. As the charcoal burns slowly, the gas is made, and as it is heavier than air, it spreads, at first, all over the floor. It gets higher and higher, and at length reaches the mouths, of the persons in the room. If they happen to be asleep, they are very apt to be killed by breathing the gas; but if they are awake, they are conscious of the unpleasant feelings the gas produces, and either go out into the air, or make some noise which brings others to their relief.
Gas sometimes in wells.
This gas sometimes collects in wells, and kills men that go down into them. Now there is one way by which we can always tell whether this gas is in a well. If there be none there, we can lower a lighted candle down to the water and it will not go out; but if there be any of this gas there, the candle will go out as soon as it reaches it.
The Grotto of the Dogs.
There is in Italy a cave or grotto, which is called the Grotto of the Dogs. The reason that this name was given to it will appear from what I will tell you about it. This deadly gas is constantly made there in some way that we do not understand. There is enough of it to reach above a dog’s head, but it never gets up as high as a man’s head. While a man, then, can breathe in the grotto perfectly well, a dog can not, for he is down in the gas. A dog is kept there by some one living close by, for the purpose of showing the effect on him to visitors. When he is carried into the grotto, he soon falls down, and would die if he were left there; but as they wish to keep him for exhibition to others, they bring him out, and though he looks as if he were dead, dashing some cold water on him and letting him breathe the fresh air soon revive him.
Gas breathed out from the lungs of animals.