be found in plants and never existed before they were made in the
laboratory. It used to be thought that organic compounds, the products
of vegetable and animal life, could only be produced by organized
beings, that they were created out of inorganic matter by the magic
touch of some "vital principle." But since the chemist has learned how,
he finds it easier to make organic than inorganic substances and he is
confident that he can reproduce any compound that he can analyze. He
cannot only imitate the manufacturing processes of the plants and
animals, but he can often beat them at their own game.

When coal is heated in the open air it is burned up and nothing but the
ashes is left. But heat the coal in an enclosed vessel, say a big
fireclay retort, and it cannot burn up because the oxygen of the air
cannot get to it. So it breaks up. All parts of it that can be volatized
at a high heat pass off through the outlet pipe and nothing is left in
the retort but coke, that is carbon with the ash it contains. When the
escaping vapors reach a cool part of the outlet pipe the oily and tarry
matter condenses out. Then the gas is passed up through a tower down
which water spray is falling and thus is washed free from ammonia and
everything else that is soluble in water.

This process is called "destructive distillation." What products come
off depends not only upon the composition of the particular variety of
coal used, but upon the heat, pressure and rapidity of distillation. The
way you run it depends upon what you are most anxious to have. If you
want illuminating gas you will leave in it the benzene. If you are after
the greatest yield of tar products, you impoverish the gas by taking out
the benzene and get a blue instead of a bright yellow flame. If all you
are after is cheap coke, you do not bother about the by-products, but
let them escape and burn as they please. The tourist passing across the