Lithium

Lithium was discovered in 1817 by Johan August Arfwedson, working in the Stockholm laboratory of Jons Jacob Berzelius, while analysing the mineral petalite. The metal itself was first isolated only later, by electrolysis, in the hands of William Brande and Humphry Davy around 1821. Its name comes from the Greek lithos, meaning stone, chosen because the new alkali had been found in a mineral, in contrast to sodium and potassium, which had been drawn from plant ashes and animal matter.

Lithium is the lightest of all metals and the least dense element that is solid at room temperature, soft enough to cut with a knife and reactive enough to be stored under oil. Its lightness and high electrochemical potential have made it the basis of the rechargeable lithium-ion batteries that power phones, laptops and electric vehicles, and it also serves in heat-resistant ceramics and glass, in lightweight aircraft alloys and as a flux in metalwork.

Lithium carries no alchemical inheritance: it was unknown as an element until the nineteenth century, long after the planetary-metal scheme had closed, so no ancient symbolism attaches to it. Its cultural resonance is entirely modern and twofold. In cosmology, lithium is one of only a handful of elements forged in the first minutes after the Big Bang, alongside hydrogen and helium, which gives it a quiet place in accounts of the universe's origin.

In medicine, lithium salts became, after John Cade's work in 1949, the archetypal mood stabiliser, so that the element's name entered ordinary speech as a byword for psychiatric steadiness. A parallel thread runs through the patent-medicine era: from the 1880s American spa towns such as Lithia Springs, Georgia marketed naturally occurring lithium-bearing water as a cure-all, and in 1929 the soft drink that became 7 Up launched under the name Bib-Label Lithiated Lemon-Soda, containing lithium citrate and advertised as a mood-lifting tonic; the ingredient was quietly removed only in 1950, decades before Cade's clinical work put lithium's psychiatric effect on a scientific footing. The element also has a harder modern use: lithium-6 deuteride is the fusion fuel of thermonuclear weapons, so the lightest of metals sits at both extremes of human use, tonic water and doomsday device.