Thomas Midgley Jr. was very good at solving problems.

This turned out to be a problem.

During the first half of the twentieth century, Midgley helped develop two technologies that seemed to answer major engineering challenges. One stopped automobile engines from knocking. The other gave refrigerators and air conditioners a refrigerant that was far safer around people than many of the alternatives then in use.

The first solution put lead into gasoline.

The second helped introduce chlorofluorocarbons, better known as CFCs.

Several decades later, the first would be recognized as a massive public-health problem and the second as a threat to the planet’s ozone layer. This is not generally considered an ideal batting average for inventions intended to improve everyday life.

And then, late in life, Midgley designed one more device to solve a personal problem.

He died entangled in it.

Thomas Midgley Jr. Was a Seriously Accomplished Inventor

It is tempting, particularly with the benefit of hindsight, to treat Thomas Midgley Jr. as history’s exceptionally unfortunate inventor—the man who somehow managed to choose the wrong answer every time someone handed him the periodic table.

That does him a disservice.

Midgley was a talented mechanical engineer who gradually became deeply involved in chemistry. Born in Beaver Falls, Pennsylvania, in 1889, he graduated from Cornell University with a degree in mechanical engineering in 1911 and eventually joined the research organization headed by famed inventor Charles Kettering.

Over the course of his career, Midgley became one of the most celebrated American industrial inventors of his generation. He received 117 patents, became president of the American Chemical Society in 1944, was elected to the National Academy of Sciences, and received the American Chemical Society’s prestigious Priestley Medal in 1941.

In other words, this was not a man wandering around a garage attaching random chemicals to household appliances to see what happened.

His inventions were celebrated because they worked.

The difficulty was what happened after they worked.

First Problem: Automobile Engines Kept Knocking

Early automobile engineers had an annoying problem known as engine knock.

In a gasoline engine, the fuel-air mixture is supposed to burn in a controlled fashion after being ignited by the spark plug. Under certain conditions, however, part of the mixture can ignite at the wrong time, producing pressure waves inside the cylinder. The resulting knocking or pinging sound is not merely irritating. It can reduce efficiency and damage an engine.

Higher-compression engines offered better performance, but increasing compression also made knocking more troublesome. Kettering’s research team therefore began looking for something that could be added to gasoline to suppress it.

They tried a remarkable assortment of substances.

Then, in December 1921, Midgley and his colleagues discovered that a very small quantity of tetraethyl lead worked extraordinarily well.

From an engineering standpoint, this was excellent news.

From the standpoint of anyone who preferred not to distribute a powerful neurotoxin through automobile exhaust, there were some details still to be worked out.

The Lead in Leaded Gasoline Was Not a Surprise

One important part of the Thomas Midgley story tends to disappear in abbreviated versions: nobody had to wait until the 1970s to discover that lead could be poisonous.

Lead toxicity had been recognized for centuries, and tetraethyl lead was dangerous enough that Midgley himself became seriously ill while working with it. In early 1923, after extensive exposure, he stepped away from his work to recover from lead poisoning.

The warning signs became considerably harder to overlook the following year.

Workers manufacturing tetraethyl lead at plants in New Jersey and Ohio suffered severe neurological symptoms. Some became delirious or psychotic. Fifteen workers died during a series of poisoning incidents in 1924, and newspapers began referring to the product with names such as “loony gas.”

This was not exactly the sort of branding General Motors had been hoping for.

The controversy led to government investigation, but leaded gasoline survived. It was remarkably effective at raising octane and allowing higher-compression engines, and it became a standard part of automobile fuel for decades.

The broader danger from putting lead into millions of automobile fuel tanks became increasingly clear over time. Beginning in the 1970s, the Environmental Protection Agency started forcing lead levels in American gasoline downward. Leaded gasoline for ordinary on-road vehicles was finally prohibited in the United States beginning in 1996.

Midgley never saw any of that.

He died in 1944, when leaded gasoline was still widely regarded as one of the great technological successes of the automotive age.

Next Problem: Refrigerators Could Kill You

If Midgley’s work had ended with leaded gasoline, his place in technological history would already have been secure.

It didn’t.

By the late 1920s, another industry had a problem that was considerably easier for consumers to understand.

Refrigerators were becoming increasingly desirable household appliances, but many of the chemicals used as refrigerants were unpleasant things to have circulating through machinery in the kitchen. Ammonia, sulfur dioxide, chloromethane, and various hydrocarbons could be toxic, corrosive, flammable, or some particularly ambitious combination of the three.

What the refrigeration industry wanted was a substance that would do its job efficiently while remaining nonflammable, chemically stable, and relatively safe if it escaped.

Midgley joined a team working on the problem for General Motors’ Frigidaire division.

Once again, he helped find an extraordinarily effective solution.

Meet Freon: The Wonder Refrigerant

Midgley and his colleagues focused on compounds containing carbon, chlorine, and fluorine. In 1928, the team developed dichlorodifluoromethane, a chlorofluorocarbon now usually called CFC-12 or R-12.

It would be marketed under the trade name Freon-12.

For the immediate problem, it was close to ideal.

It was stable. It was nonflammable. Under normal conditions it was far less acutely toxic than many of the refrigerants it could replace.

Midgley was sufficiently enthusiastic about those properties that, during a 1930 presentation before the American Chemical Society, he inhaled some of the vapor and then exhaled it over a flame, extinguishing the flame.

In one demonstration he showed that the new refrigerant was both sufficiently low in acute toxicity for him to breathe it briefly and sufficiently nonflammable to put out a fire.

It was the sort of scientific demonstration that made an impression.

Modern laboratory safety officers would probably prefer a PowerPoint presentation.

Unfortunately, Freon’s Best Feature Was Also Its Worst

The quality that made CFCs so useful was their stability.

They did not readily react with other substances near Earth’s surface. That made them remarkably convenient for refrigeration, air conditioning, aerosol products, and other applications.

It also meant that when CFC molecules escaped into the atmosphere, they could remain there for a very long time.

In 1974—thirty years after Midgley’s death—chemists Mario Molina and F. Sherwood Rowland published research showing what eventually happened to those extraordinarily stable molecules. CFCs could drift upward into the stratosphere, where intense ultraviolet radiation broke them apart and released chlorine atoms.

Those chlorine atoms could then participate in reactions that destroyed ozone.

The ozone layer protects life on Earth by absorbing much of the Sun’s harmful ultraviolet radiation.

It turned out that creating a chemical famous for refusing to react with practically anything was an excellent idea right up until it reached the one part of the atmosphere where that became a serious problem.

The history of twentieth-century chemistry is filled with substances that turned out to have much larger careers than anyone anticipated. Teflon provides another particularly good example: it was accidentally discovered during research into new refrigerants and eventually became famous for something entirely different.

Midgley Did Not Know What CFCs Would Do to the Ozone Layer

This is where the story needs more nuance than the popular version usually gives it.

The hazards of Midgley’s two most famous technologies were not equally foreseeable.

Lead was known to be poisonous. Midgley personally suffered lead poisoning, workers died while producing tetraethyl lead, and serious questions about public health accompanied leaded gasoline almost from the beginning.

The ozone-destroying properties of CFCs were different. The atmospheric chemistry that made them dangerous was not identified until decades later. In Midgley’s lifetime, their chemical stability and low acute toxicity were regarded as virtues—and for the problem he had been asked to solve, they genuinely were.

That distinction matters.

Midgley’s story is more interesting if he is not reduced to a cartoon villain wandering from laboratory to laboratory asking what else he could poison.

He was a talented inventor solving real problems, often very successfully.

The consequences simply extended far beyond the problems he had been asked to solve.

Then Polio Gave Midgley One More Problem to Solve

In 1940, at the age of 51, Midgley contracted polio and was left with severe physical disabilities.

Once again, he approached the situation as an engineer.

Midgley devised an arrangement of ropes, pulleys, and a harness that helped him move between his bed and wheelchair without requiring someone else to lift him.

Then, on November 2, 1944, Midgley was found dead at his home in Worthington, Ohio. He had been strangled by the apparatus he designed to help himself move.

For decades, biographies supplied an almost unbearably perfect ending to the story: the inventor whose inventions produced disastrous unintended consequences had finally been accidentally killed by one of his own inventions.

There is just one problem.

The accident may not have been an accident.

Was Thomas Midgley Killed by His Own Invention?

Contemporary accounts did describe Midgley’s death as accidental. The American Chemical Society’s 1944 obituary said he had accidentally become entangled in the apparatus while sleeping. Time likewise reported accidental strangulation.

That version became part of the Midgley legend.

Later historical research uncovered a substantial complication: Midgley’s death certificate reportedly identified the death as suicide by strangulation. Historian Carmen Giunta also found evidence that chemist Albert Henne, who knew Midgley and was called to the house after his death, privately believed it was not an accident.

Consequently, the irresistible statement that “Thomas Midgley was accidentally killed by his own invention” should be treated with caution.

What can be said with confidence is strange enough: Midgley designed a rope-and-pulley apparatus to compensate for his disability, and he died of strangulation involving that apparatus.

History has apparently decided that anything beyond that requires a footnote.

This is just one more of countless examples of solutions that created problems far larger than the ones they were intended to fix. Midgley’s story is especially striking because his solutions did exactly what they were supposed to do.

Thomas Midgley’s Real Legacy Is Unintended Consequences

It is easy to look backward at Thomas Midgley Jr. and marvel at the odds of one person becoming centrally associated with both leaded gasoline and CFC refrigerants.

But the more interesting lesson is not that Midgley was uniquely bad at inventing things.

He was alarmingly good at it.

Tetraethyl lead really did suppress engine knock. CFC refrigerants really were nonflammable, stable, and far less immediately hazardous than many of the substances they replaced. His inventions became enormously successful precisely because they solved the problems they were designed to solve.

The trouble was that the definition of the problem was too small.

An engineer looking at an engine asked, “How do we stop it from knocking?”

A refrigeration engineer asked, “How do we make refrigerators safer?”

Both questions got excellent answers.

Nobody had yet worked through the considerably larger questions about what would happen when billions of gallons of leaded fuel were burned or when extremely stable chlorine-containing compounds accumulated in the atmosphere for decades.

Thomas Midgley therefore makes an unusually good patron saint of unintended consequences.

He reminds us that sometimes the most dangerous invention is not the one that doesn’t work.

It is the one that works beautifully.

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