Phosphorus

Category: non-metal Atomic number: 15 Colour: white, red, violet or black Melting point (white): 44°C (111°F) Sublimation point (red): 416–590°C (781–1,094°F) Boiling point (white): 280°C (537°F) First identified: 1669

Phosphorus was the thirteenth element to be discovered. It has sometimes been called the devil’s element, due to the unlucky nature of the number 13 and to some of its other unpleasant properties. It was discovered in 1669 by the German alchemist Hennig Brand – while searching for the philosopher’s stone, he boiled up and evaporated a huge vat of urine that had been left to ripen for days (which must have created a pretty vile smell). When he reheated the residue, it emitted glowing phosphorous vapour, which he condensed. It was Lavoisier, a century later, who recognized and named the element phosphorus, which means ‘light bearer’ in Ancient Greek. An easier production method used was to dissolve animal bones in sulphuric acid to form phosphoric acid, which is then heated with charcoal to produce white phosphorus.

Different allotropes and forms of phosphorus come in different colours – the most common ones are white phosphorus – which is poisonous, dangerously flammable in air, glows in the dark and can cause nasty burns on contact with skin – and red phosphorus – a safer type that you find in the material on the side of matchboxes. White phosphorus was used in matches such as those manufactured in Stockton-on-Tees in the UK from 1827 onwards; however, many of the girls who worked in the factory producing these were afflicted by ‘phossy jaw’, a nasty disease that caused the jawbone to waste away, and so this use was banned early in the twentieth century.

Phosphorus has been used in some deadly weapons, from tracer bullets, fire bombs and smoke grenades to the phosphorus bombs that caused terrible firestorms in Hamburg in 1943. It has also been used in nerve gases such as sarin, which killed or damaged many people in the Iraq–Iran war in the 1980s (as well as killing twelve and harming many other people in the Tokyo subway attack in 1995).

Happily, you don’t find phosphorus in nature – only phosphates, which are crucial to life in a variety of ways and found in DNA, tooth enamel and bones: we consume them in foods such as tuna, eggs and cheese. Phosphates are also used as fertilizers, which have enabled humanity to hugely increase agricultural production in recent centuries. But we may be heading for serious problems in the phosphorus cycle. On the one hand, using too many phosphates in fertilizers or detergents has led to pollution of rivers and lakes, which encourages algae to grow, harming water-dwelling organisms that rely on photosynthesis and, as a result, other species that need the oxygen they produce. At the other end of the scale, we may be within a few centuries of running out of sources of phosphate. Guano, manure and human excreta were sources of phosphates in the past, but the only economically viable source now is phosphate rock from a limited number of places.

Enemy of the People

Antoine Lavoisier was a member of the French establishment, working for the customs and tax organization, the Ferme générale. His political connections helped fund his brilliant research but contributed to his downfall in the end. In 1794, after the French Revolution, he was charged with tax fraud during the Reign of Terror and went to the guillotine.

At the same time as we have been pumping out too much phosphorus into the environment (in forms that aren’t easy to reclaim as usable phosphates), we have been removing the phosphates that support current levels of food production at an accelerating rate. Many scientists expect this to be one of the major environmental crises of the next one hundred years, even if the issue is currently below most people’s radars.