Fig. 14.—Simple gas-making.
Very soon you will notice a light-colored smoke issuing from the mouthpiece, but after a time this smoke disappears. But what happens if you hold a lighted match to the mouthpiece of the pipe? Immediately a bright yellow flame appears ([Fig. 14]).
The gas now burning is the same gas as is burnt in your house, although this latter, of course, is much purer.
If now you take the pipe from the fire, allow it to cool and then break it, you will be surprised to find that its contents have changed in appearance, for, in place of the coal, you will see what looks like a cinder. This is the coke. Thus you have manufactured gas from coal, at the same time producing coke.
Experiments with Carbonic Acid Gas
In a [previous chapter], when describing how to make a miniature cannon, it was explained that the “gunpowder” with which the “shell” was fired is in reality carbonic acid gas.
It may not be amiss to show how to generate it, in order that you may discover for yourselves some of its properties.
There are several ways of obtaining carbonic acid gas, but most of these are of a complicated nature. The following, however, is an extremely simple method.
Take a 6-oz. or 8-oz. flask, and fit it with a cork with a hole, in which may be fitted a piece of glass tubing.
This tubing should be bent twice at right angles, as shown in [Fig. 15], and the longer end should be allowed to dip into a large glass.