Question

Why the iron pillar don't get rusted?

Answer 1

Metallurgists discovered that a thin layer of "misawite", a compound of iron, oxygen and hydrogen, has protected the cast iron pillar from rust.The relatively pure composition of the iron used, presence of high amounts of phosphorus (as much as 1 per cent against less than 0.05 per cent in today's iron) and absence of sulphur/magnesium in the iron are the main reasons for its longevity.