The Delhi Pillar

THE freedom from rusting of the famous iron pillar at Delhi has long been a subject of comment and has been attributed by some writers to the peculiar properties of the ancient iron from which it is forged. Although some particulars of its history are obscure, it seems certain that the pillar dates from about the fifth century A.D. and is roughly 1,500 years old. The immunity of iron from rusting over such a long period is a striking phenomenon and it may therefore be of interest to report the results of some experiments that were made to ascertain the reason for this.