EslodgKv Leaded fuel Thomas Midgley Jr 4
Leaded fuel Thomas Midgley Jr 4

Poor Tom put the lead in petrol

HOW many people remember the days of leaded petrol in Australia?

It was the only fuel from the early 1920s right up to 1985, when the Federal Government announced that all new petrol-engined cars would need to have catalytic converters and run on unleaded petrol.

I was annoyed because I’d bought a new Subaru just before ULP arrived and the new brew was of a miserable 91 octane, compared to 97 in leaded super.  

Also, it turned the light grey tailpipe to a sooty black.

However, that was remedied by fitting a Fuelstar catalyst, which re-introduced lead to the mix, reinstated the grey to the tailpipe and added a modicum of performance.

Similar products were Fitch in the US and Powerplus in the UK.

By the time I’d sold the Subaru, ULP was available in 95 octane as well, and years later in 98. 

But petrol has quite a history.

It started in 1859 when Edwin Drake dug the first crude oil well in Pennsylvania and distilled the oil to produce kerosene for lighting. 

Although other petroleum products, including petrol, could also be produced in the distillation process, cars had not yet been invented, so there was little use for anything other than kerosene and oil. 

In Germany in 1888, Karl Benz’s wife, Bertha, made the world’s first car journey by driving his motorwagen from Mannheim to Pforzheim. 

It made her a pioneer of modern travel on land — and of fuel.

There were no servos, but ligroin, a petroleum-based product used mainly for cleaning, was available from pharmacies. So that’s where Bertha headed when she reached the town of Wiesloch.

A few years later that pharmacy laid claim to being ‘the world’s first filling station.’ 

By 1920, more than 9 million petrol-powered vehicles were on the road worldwide and service stations selling petrol, oil, tyres and other motoring essentials were popping up everywhere.

However, the basic petrol left the cars prone to pre-ignition problems.

Enter Thomas Midgley Jr

He was a chemist, born in the US in 1889 into a family of inventors, and was working at General Motors from 1916 with the famous Charles Kettering, the founder of Delco, and head of research at GM.  

After countless experiments, Midgley  discovered that noisy engine knock from pre-ignition could be stopped by adding certain chemical compounds, the most effective being tetraethyl lead.

It stopped the knocking in combustion engines and its lubricating properties greatly improved performance. 

In December 1922, he was awarded the Nichols Medal of the American Chemical Society for the “Use of Anti-Knock Compounds in Motor Fuels” and became general manager of the newly-created Ethyl Gasoline Corporation which  produced and marketed the new wonder fuel, which was first sold at a petrol station in Dayton, Ohio, in 1923.

The high toxicity of lead was already known at that time, but advertising for the brew used the term ‘ethyl’ rather than lead.

By 1923 every petrol-engined vehicle in the US, and soon after, the entire motorised world, including aircraft, was running on Tom Midgley’s fuel.

It was so popular that several thousand baby girls born in the US were named Ethyl. 

Through the years octane rating of fuel was increased, with 100 called avgas or aviation fuel — it was the top spec. 

But health hazards associated with the fuel generated negative headlines so in October 1924, Midgley called a press conference to show how harmless tetraethyl lead was.

He poured tetraethyl lead over his hands, sniffed and inhaled the vapour from a bottle of the fuel for 60 seconds and said: “I could do this every day without getting any health problems whatsoever.”

However, soon after, he was diagnosed with serious lead poisoning and it took more than a year for him to recover.

First gas station to sell leaded gasoline. Dayton Ohio February 1923
First gas station to sell leaded gasoline. Dayton, Ohio, February 1923.


Despite that, the fuel quickly captured the market and by 1925, more than a billion litres had been sold. 

It took another 50 years before the world accepted that while leaded fuel was great for engines, it was very much less so for people, plants and the environment.

So unleaded petrol, ULP, came into being, initially in 91 octane with higher octanes 95 and 98 arriving on the market later.

The US started phasing out leaded fuel in the mid-1970s and banned it in 1996.

In the European Union, leaded fuel was banned on January 1, 2000 —  Australia two years later. 

ULP has its own batch of ingredients, including alkanes, olefins and aromatics like benzene, toluene, xylene, methanol and metal deactivators, like cyclohexanediamine.

On an entirely different level: Cars have long had air conditioning, and that’s another thing invented by Tom Midgley.

In the late 1920s, compounds like ammonia, methyl chloride or sulphur dioxide were used as refrigerants in air conditioning and refrigeration systems. All were either toxic, highly flammable or  explosive. 

The smallest leakage could result in serious illness, injury or even death.

But Thomas Midgley Jr developed cheaper and safer refrigerators. 

He developed a gas that replaced the numerous nasties previously used as refrigerants and made refrigerators safe. 

His new refrigerant was non-toxic and non-flammable, and he called it Freon 12 — because its proper name was dichlorodifluoromethane.

Again sceptics said it was potentially harmful, but he shut them down in 1930 by inhaling a lungful of Freon 12 and then blowing out a lit candle, proving it was neither toxic nor flammable.

 By 1950 more than 90 per cent of urban homes and 80 per cent of American farms had Freon-powered fridges.

That flowed on to air conditioning, fire extinguishers and aerosol spray propellants and in 1937 earned him the Society of Chemical Industry’s Perkin Medal.

But the Freon stuff was later known as CFC and scientists realised it was responsible for ozone-depleting and greenhouse gas effects in the atmosphere.

Worldwide production of CFCs was phased out by 2005.

So despite his best intentions, Thomas Midgley Jr’s two inventions actually had a fatal impact on the Earth‘s atmosphere. 

At the time of his discoveries, Midgley was an American national hero.

He was to invent one more thing: a bed with an elaborate system of cables.

He had contracted polio, which left him severely disabled, and the pulleys helped him sit up in bed.

But in November, 1944, something went wrong and he became entangled in the cables, which strangled him to death.

President of the American Chemical Society William Lloyd Evans paid tribute to him:  “In a wonderful way Thomas Midgley Jr made life more enjoyable. The after-world will appreciate the enduring value of his research.”

In hindsight those turned out to be bittersweet words. 


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