There is a remarkable column in Delhi which has stood there for many centuries. It is remarkable because it is made of pure iron. Time has no effect on it. Ages have passed, but the column still looks quite new. It does not rust. As if corrosion had in this case betrayed its habits. . .

    How the ancient metallurgists succeeded. in producing pure iron is quite a puzzle. Some hotheads have contended that it was not even made by man. That visitors from other worlds had put up this obelisk to commemorate their arrival on Earth.

    But if we deprive the column of the mysterious aureole of its origin there remains a fact which is very important to chemists, namely, that the purer a metal is, the slower it is attacked by corrosion. If you want to conquer corrosion, use the purest metals possible.

    And not only purity is important; it is also necessary to give the surface of the metallic article as high a finish as possible. It appears that separate "hills" and "valleys" can play the part of foreign inclusions. Scientists and engineers have succeeded in obtaining almost ideally smooth surfaces. Articles with such surfaces have already found usage in the construction of rockets and spaceships.
 

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