Silver

Category: transition metal Atomic number: 47 Colour: silver, of course Melting point: 962°C (1,764°F) Boiling point: 2,162°C (3,924°F) First identified: prehistory

Silver is a native metal that can naturally be found in pure form, so we have known about this beautiful shiny metal for 10,000 years or more. It was probably first extracted from ores in the area of ancient Turkey and Greece by the Chaldeans in about 3000 BC using ‘cupellation’. This is a method whereby molten metal ores (containing, for instance, lead-zinc, copper or copper-nickel) are heated in a cup over which air is blown – the other more reactive metals are thus oxidized and the molten silver is isolated.

It was used from around this time for coins, as well as for luxury household items. It has often been strengthened by the addition of copper or other metals, in which case it is known as sterling silver. Unlike its precious-metal cousin, gold, silver does tarnish – it gradually becomes darker and duller as it reacts with sulphur to form silver sulphide on the surface, which has to be polished off regularly. But it has nonetheless been valued highly throughout history.

If you’re fond of either mirrors or selfies, silver has played a key role in the development of these ways of admiring yourself. Due to its reflectivity, it was historically the main metal used in making the backs for mirrors (although the cheaper aluminium is usually used now). In 1727, Johann Heinrich Schulze (a German scientist) made a slurry of chalk and a silver nitrate salt and found that it was blackened by the light. After experimenting by making images with stencils, he had created the origins of the science of photography – the separation and combination of ions on the surface of the mixture was forming darker and lighter areas (although Schulze was unable to fix and keep this image). In 1840, Henry Fox Talbot worked out how to fix the image on paper coated in silver iodide using gallic acid, and all the necessary pieces were in place.

Of course, modern selfies are digitally created without the need for the original chemical processes, but it’s worth taking a moment to appreciate what a magical discovery it was at the time. And even in our modern age, silver is finding new applications – it is now possible to scroll through the images on your phone wearing gloves that have silver thread sewn into the fingertips, so that the touchscreen can be used without you getting cold hands.