Letter: Spare a nickel?

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The Independent Online
Sir I feel Dr James Hutchison (letter, 21 November) is wrong in attributing the magnetism of "copper" coins to their iron content.

Iron is not the only metal to exhibit magnetic properties, which are shared by nickel and cobalt. I suggest the case in point is caused by variations in the coins' nickel content, which is included to harden the metal.

Dr P HOLMES

Newcastle-upon-7Tyne

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