What exactly does the “smell of money” smell like?

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In ancient China, there was a prejudice against merchants, saying that merchants all had a "copper smell". There is a saying that merchants are exposed to copper coins all year round, so they will be tainted with that unique smell. If we think about it carefully, we often encounter this situation in life. It is true that we can smell rust occasionally, or there will be an indescribable smell on our hands after touching coins. Does metal really have a smell?

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To understand this, we must first understand the prerequisites for smelling. To smell, two conditions are required: first, the substance must be able to volatilize or evaporate to form gas molecules or vapor. And these gases or vapors must be able to combine with the receptors in the nose .

However, the atoms that make up metals have strong bonding forces, and most metals have high melting and boiling points, making them difficult to evaporate.

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Since metals do not emit odor molecules in these two ways, where does the metallic smell we smell come from? Some scientists have found that the "metallic smell" produced by touching metal is actually some aldehydes or ketones formed by the catalytic oxidation reaction between human secretions and metal. These substances are the source of the metallic smell .

Image source: Tuchong Creative (unauthorized reproduction)

For example, when iron products come into contact with the skin, the sweat secreted by the human body will promote the oxidation of part of the iron in the iron products into ferrous ions, and further catalyze the decomposition of peroxide esters on the skin surface. The so-called rust smell is actually the smell produced by the decomposition of peroxide esters.
Therefore, the so-called metallic smell is not produced by the volatilization of the metal itself, but is achieved through chemical reactions to form odorous organic molecules.

In other words, the "copper smell" or "metallic smell" we smell is just our own body odor .

Reviewer: Xiong Bin, Associate Professor, College of Chemistry and Chemical Engineering, Hunan University