Ozone

Ozone wasn't invented—it was discovered by Christian Friedrich Schönbein in 1839 at the University of Basel while investigating electrolysis of water. He noticed a distinctive odor from electrical sparks, the same smell that follows lightning strikes. The name comes from Greek ozein: "to smell." But identifying the smell as a distinct chemical species—O3 rather than O2—required understanding that oxygen could exist in multiple allotropic forms.

What had to exist first? The concept of elements and allotropes. Oxygen had been isolated in the 1770s, but the idea that the same element could form molecules with different structures took decades to develop. Electrolysis technology to generate ozone artificially. And critically, analytical chemistry advanced enough to distinguish ozone from other reactive oxygen species.

The peculiar smell masked extraordinary reactivity. Ozone is oxygen with an extra atom—three oxygen atoms bonded in an unstable configuration that desperately wants to shed one and return to O2. This makes ozone one of the strongest oxidizers available: it attacks organic molecules, destroys bacteria, breaks down pollutants. Where oxygen rusts iron slowly, ozone does it violently.

By the late 19th century, this oxidative power found application in water treatment. Ozone kills microorganisms without leaving residues like chlorine does. It breaks down organic contaminants without generating secondary pollutants. The first municipal ozone water treatment plant opened in Oudshoorn, Netherlands in 1893. Paris adopted ozone treatment in 1906. The technology spread wherever water quality mattered more than treatment cost.

The ozone layer discovery in the 1920s revealed that the same molecule protects Earth from UV radiation. Ozone in the stratosphere absorbs ultraviolet light that would otherwise sterilize the surface. The same chemical that destroys microorganisms in water treatment protects life at altitude. This created the modern environmental paradox: ozone depletion in the stratosphere threatens ecosystems; ozone production at ground level pollutes air.

Ozone exhibited path dependence in industrial applications. Once water treatment plants invested in ozone generators and distribution systems, switching to alternatives required replacing infrastructure. Chlorination was cheaper but left taste and created carcinogenic byproducts. Ozone cost more but provided purer water. The selection pressure for quality locked in ozone for high-value applications.

Today, ozone treats drinking water in major cities worldwide. Medical applications exploit its oxidative properties for wound sterilization and surgical equipment disinfection. Food processing uses ozone to extend shelf life without chemical preservatives. Semiconductor manufacturing uses ozone in photoresist stripping and wafer cleaning. Every application exploits the same unstable O3 molecule that Schönbein smelled in 1839.

The molecule's persistence reveals a deeper pattern. Ozone wasn't designed for any application—it's a consequence of oxygen chemistry. But once humans identified it, the same oxidative instability that makes ozone unstable makes it useful. The conditions created the discovery; the discovery created applications; the applications became locked in through infrastructure investment. The smell of lightning became the foundation for modern water treatment.