Bromine

Bromine was discovered in 1826 by the young French chemist Antoine-Jerome Balard, who obtained it from the residues of seawater and sea salt; Carl Lowig had reached it independently. Its name comes from the Greek bromos, stench, chosen for the foul, penetrating odour of its dense reddish-brown vapour. Bromine is one of only two elements liquid at room temperature, the other being mercury, and belongs to the reactive halogen family. Denser than water and giving off a corrosive vapour, bromine and its compounds have been used in flame retardants, in agricultural fumigants, in photographic film and in some dyes and medicines, though a number of these uses have been curtailed on health and environmental grounds.

Potassium and sodium bromide salts were widely prescribed as sedatives and anticonvulsants from the mid nineteenth century into the twentieth, common enough that a bromide entered English as an idiom for a dull, soothing, unoriginal remark or platitude, a linguistic trace of the medicine cabinet that has long outlasted the drugs themselves, which were phased out after longer-term toxicity became clear. Today the Dead Sea, with one of the highest natural bromide concentrations on Earth, supplies a large share of the world's bromine through evaporation and extraction works on its Israeli and Jordanian shores.

Bromine's name records nothing more than its evil smell, but the element carries an unexpected thread of ancient prestige. The famous Tyrian purple of the Phoenicians and of Roman imperial robes, the dye extracted at great labour from the murex sea-snail and reserved for the highest ranks, is chemically a dibromoindigo, its regal colour owed to the very bromine atoms that Balard would isolate from the sea more than a millennium later. The element itself has no alchemical or mythological history, being a nineteenth-century discovery, but through the murex dye its atoms sat, unrecognised, at the heart of one of the ancient world's most potent symbols of rank and power.

Producing a single gram of genuine Tyrian purple dye required processing many thousands of murex sea-snails, a labour cost that made the finished cloth worth more than its weight in gold in the ancient Mediterranean; Roman sumptuary laws eventually restricted the deepest purples to the emperor alone, so that purpura became a literal marker of imperial rank rather than mere fashion. The dye works of Tyre and Sidon were famous, and reportedly foul-smelling, industrial sites of the Phoenician coast for over a thousand years before synthetic dyes, unrelated to bromine, made purple cheaply available to everyone in the nineteenth century.