The Scientist: Thomas Midgley, Jr.

There is a limited number of people for whom contracting polio could be morbidly viewed as a good thing. But according to British comedian Phil Jupitus, when “the human being in history who has done the most damage to the environment” contracted a chronic disease, the world was better off for it.

This menace was Thomas Midgley Jr., class of 1911 — one Cornell alumnus seldom bragged about during tours of Sibley School of Mechanical and Aerospace Engineering.

To many environmentalists, Jupitus’ comment may seem appropriate. Midgley’s inventions, the tetra-ethyl lead (TEL) additive in gasoline and chlorofluorocarbon (CFC) refrigerants, became two of the most talked about chemical pollutants in human history.

Lead is a dangerous neurotoxin that can cause nausea, insomnia, impaired cognitive function and in extreme cases seizures, comas and death.

Chlorofluorocarbons break apart in the Earth’s atmosphere, releasing fluorine atoms that diminish the ozone layer. As this layer of gas wears away, more ultraviolet radiation from the sun reaches the earth’s surface, increasing the incidence of skin cancer in humans and increasing the amount of toxic ozone gas in breathable air.

After Midgley graduated with a degree in mechanical engineering, Charles Kettering, a notable inventor himself (he sometimes said that Midgley was his greatest discovery), recruited the young scientist to work in the lab at General Motors.

His first invention, tetra-ethyl lead, was designed to reduce a condition in cars called “engine knock.” In a car engine, a piston compresses a mixture of gasoline and air to compress fuel, which is ignited by a spark to release energy. This controlled combustion pushes the piston back again so the process can repeat.

Prof. Albert George, mechanical engineering, explained, “What happens [with knocking] is, you try to compress a mixture of fuel and air and it explodes by itself before you get a chance to put a spark in. When that happens, it’s an explosion rather than a controlled burn. … [The explosion] both melts things, and physically damages them.”

Usually, more compression means a more efficient engine. However, if a fuel is compressed too much, the engine will knock.

In order to remedy this problem, additives are mixed with the fuel to increase its octane rating — its ability to be compressed without exploding. When Midgley was assigned to remedy the problem of engine knock, there were additives that could reduce knock but none that effectively get rid of it.

Midgley was not a chemist, but he was clever. His boss Charles Kettering observed of him in a biography, “Midgley's interest in the periodic table caused him to carry a copy of it with him constantly.” Working his way through the table, Midgley discovered that when added to gasoline, certain elements significantly reduced engine knock. None, however, were more effective than lead.

Lead was such an effective antiknock agent that all one had to do was wave a TEL soaked cloth in front of the intake of a knocking engine and the sound would almost immediately stop. According to Prof. Elizabeth Fisher, mechanical engineering, “As a combustion person, you can see how excited you would get over something like this. It was incredibly effective.”

CFCs were a similarly miraculous discovery. Refrigerants at the time were harmful in their own right. A refrigerant leak in a Cleveland hospital in 1929 killed over 100 people. “To put this in historical perspective,” Prof. Ke Zhang, mechanical engineering said, “Before CFCs, the coolants [were] toxic gases, like SO2 and ammonia.”

Charles Kettering asked Midgley to work on a safer alternative to the toxic refrigerants. Midgley agreed and began to experiment systematically as he had with engine knock. Again, he followed the periodic trends and within three days he had discovered chlorofluorocarbons.

It was not until long after Midgley died that three chemists discovered the environmental effects of CFCs. “The three chemists got Nobel prizes by figuring out how the CFC[s] caused the ozone problem.” Zhang said.

Fifty years ago, no one imagined that CFCs would have such a negative effect on the environment. Likewise, both Fisher and George agreed that there is no sure way to tell if we are using a chemical today that might be surreptitiously munching at our atmosphere or leeching the health out of our bodies.

“A little known fact is that [TEL] wasn’t phased out for its health effects,” Fisher said. “It was phased out because of catalytic converters. We were ready to start controlling various air pollutants and the way to do that was to introduce catalytic converters and the converters couldn’t tolerate lead.”

Today’s engineering students are being taught to consider environmental impact. In systems engineering, George said, students are taught to keep track of their inputs and outputs from the time the needed materials are obtained to the time when they are thrown away.

Zhang said an increasing number of students enter the engineering school focused on building spaceships, but end up more interested in the fields like sustainable energy. To these students, Midgley’s story may serve as a cautionary tale.