"Well," said Fred, "teacher had a long clay pipe filled with coal broken very fine, and closed up with clay just as we had. He fixed the bowl of the pipe over the flame of a gas-burner standing on the table. He turned the stem of the pipe so as to make the end of it dip into a bowl of water.
"He then filled a glass tube with water, and turned it upside down in the basin, taking care to keep the mouth of the tube below the surface ofthe water, and just over the end of the
pipe stem. The water did not run out of the tube, but remained in it, while he held it there.
"Presently, as the bowl of the pipe got red-hot, the gas began to come out of the stem, and you should have seen what took place then. The gas rose through the water in little bubbles, and the bubbles ran up the tube one after another. As they ran up, the water began to flow out of the tube into the basin. In a little while it was all gone, and the tube was full of gas instead." "Yes, and we knew it was really the coal-gas," said Will, " because when teacher took the tube out of the water and put a light to the mouth of it, it tookfire and burned.
"Teacher says this is just the way the gas is made at the great gas-works.
