Iron rusts for the same reason that a stone rolls down hill, because it gets rid of its energy that way.  All things in the universe are constantly trying to get rid of energy except man, who is always trying to get more of it.  Or, on second thought, we see that man is the greatest spendthrift of all, for he wants to expend so much more energy than he has that he borrows from the winds, the streams and the coal in the rocks.  He robs minerals and plants of the energy which they have stored up to spend for their own purposes, just as he robs the bee of its honey and the silk worm of its cocoon.

Man’s chief business is in reversing the processes of nature.  That is the way he gets his living.  And one of his greatest triumphs was when he discovered how to undo iron rust and get the metal out of it.  In the four thousand years since he first did this he has accomplished more than in the millions of years before.  Without knowing the value of iron rust man could attain only to the culture of the Aztecs and Incas, the ancient Egyptians and Assyrians.

The prosperity of modern states is dependent on the amount of iron rust which they possess and utilize.  England, United States, Germany, all nations are competing to see which can dig the most iron rust out of the ground and make out of it railroads, bridges, buildings, machinery, battleships and such other tools and toys and then let them relapse into rust again.  Civilization can be measured by the amount of iron rusted per capita, or better, by the amount rescued from rust.

But we are devoting so much space to the consideration of the material aspects of iron that we are like to neglect its esthetic and ethical uses.  The beauty of nature is very largely dependent upon the fact that iron rust and, in fact, all the common compounds of iron are colored.  Few elements can assume so many tints.  Look at the paint pot canons of the Yellowstone.  Cheap glass bottles turn out brown, green, blue, yellow or black, according to the amount and kind of iron they contain.  We build a house of cream-colored brick, varied with speckled brick and adorned with terra cotta ornaments of red, yellow and green, all due to iron.  Iron rusts, therefore it must be painted; but what is there better to paint it with than iron rust itself?  It is cheap and durable, for it cannot rust any more than a dead man can die.  And what is also of importance, it is a good, strong, clean looking, endurable color.  Whenever we take a trip on the railroad and see the miles of cars, the acres of roofing and wall, the towns full of brick buildings, we rejoice that iron rust is red, not white or some leas satisfying color.