Red phosphorus

White phosphorus had been known since 1669, when Hennig Brand isolated it from boiled urine in his quest for the philosopher's stone. The element glowed eerily in the dark, ignited spontaneously in air, and was devastatingly toxic. By the 1830s, these very properties made it central to the lucrative match industry. 'Lucifer' matches coated with white phosphorus could be struck anywhere, igniting with satisfying reliability. But the workers who made them paid a terrible price.

Match factory workers developed 'phossy jaw'—phosphorus necrosis of the jawbone. The condition began with toothaches, progressed to abscesses, and ended with the jaw literally rotting away while the victim was still alive. The bone would glow green in the dark from absorbed phosphorus. Death often came from organ failure. The disease afflicted thousands, predominantly young women and children who worked the dipping rooms where matches were coated. Everyone knew white phosphorus was the cause. No one knew an alternative.

Anton von Schrötter, a chemistry professor at the Vienna Polytechnic, discovered one in 1845. While investigating the properties of phosphorus, he found that prolonged heating in a sealed vessel transformed the waxy white element into a completely different form: a reddish-brown powder that was stable in air, did not glow, and was essentially non-toxic. He had discovered red phosphorus, an allotrope—the same atoms arranged differently, with radically different properties.

The discovery was a direct product of institutional chemistry. Schrötter had the equipment for controlled heating experiments, the theoretical framework to recognize allotropy, and the professional context that made systematic investigation of known elements valuable research. His laboratory at what would become TU Wien represented the maturation of chemistry from alchemy into systematic science. Without the institutional apparatus of a polytechnic, the discovery might have waited decades.

The transformation from white to red phosphorus is irreversible under normal conditions. The white form consists of discrete P4 tetrahedra—highly reactive, volatile, eager to combine with oxygen. Heating breaks these molecules apart and allows them to link into polymer chains, creating a stable network structure. The same element becomes, for practical purposes, a different substance.

Yet red phosphorus alone did not solve the match problem. It would not ignite from friction as white phosphorus did. The solution required splitting the ignition chemistry between match and surface. Johan Edvard Lundström and his brother Carl Frans in Sweden developed the safety match in 1855: the match head contained potassium chlorate and sulfur but no phosphorus; the striking surface contained red phosphorus and powite. Striking produced enough heat to ignite the phosphorus, which then ignited the match head. Neither component alone was dangerous.

The safety match gradually replaced the lucifer match, though economic and consumer pressures delayed the transition for decades. Strike-anywhere matches remained popular because they were more convenient. It was not until 1906 that the Berne Convention restricted white phosphorus matches internationally, finally ending phossy jaw as an industrial epidemic. Schrötter's discovery had created the possibility sixty years earlier; social and regulatory change was required to realize it.

Red phosphorus today has applications far beyond matches. It serves as a flame retardant, a semiconductor dopant, and—notoriously—a precursor in methamphetamine synthesis. The same stability that made it safe for match workers makes it useful wherever controlled phosphorus chemistry is needed. The allotrope that Schrötter found while heating phosphorus in his Vienna laboratory remains industrially significant nearly two centuries later.