Thomas Midgley, Jr. (1889–1944), a prolific inventor known to his acquaintances as “Midge,” was born in Beaver Falls, Pennsylvania. In the Betts Academy, a small, private college preparatory school, his chemistry teacher introduced him to the periodic table, which later led him to his two greatest discoveries—tetraethyl lead (TEL) and chlorofluorocarbons (CFCs). After receiving his Ph.D. in mechanical engineering from Cornell University, Midgley became a drafter and designer at the National Cash Register Company in Dayton, Ohio.
Midgley decided on a research career because at NCR he had learned of developments made there by Charles Franklin (“Boss Kett”) Kettering, an extremely successful and prolific research director, who later referred to Midgley as “the greatest discovery I ever made.” In 1916, Midgley joined the Dayton Engineering Laboratories Company (Delco), which Kettering had founded to develop and manufacture inventions for automobiles. Midgley was assigned the task of reducing knocking in internal combustion engines, which led to what was called in 1944 “the most important automotive discovery of the last two decades.”
Tetraethyl Lead
After speculating that dyeing kerosene red might cause it to absorb heat faster so its droplets vaporize enough to prevent knocking (an untenable theory), Midgley added iodine to the fuel, which performed without knocking. However, iodine added more than a dollar to the price of a gallon of fuel and corroded the engine parts. Midgley then tested at least one compound of each chemical element to find a better additive.
After several years of fruitless search on an Edisonian trial-and-error procedure, he began a “fox hunt”—narrowing the field by a systematic investigation of compounds based on the periodic table. On December 9, 1921, after about 33,000 compounds had been tested, his team tested 0.025% of TEL in kerosene in a Delco-Light engine and found it gave better results than 1.3% aniline, their adopted standard. The long search for an antiknock agent had ended, and the process of manufacturing, development and marketing began.
Kettering thought the deficiencies in “ethyl gas” could be remedied more quickly if customers’ reactions were observed. He pushed for marketing even before the problem of lead deposits in the engine had been solved. The first public sale occurred on February 1, 1923, in Dayton. In August 1924, General Motors and Standard Oil of New Jersey founded Ethyl Gasoline Corporation.
Actions against TEL
The problem of TEL toxicity was addressed for more than three-quarters of a century. The manufacturing process is hazardous and led to new and more stringent safety regulations. In 1924 and 1925, workers at the manufacturing plants died after becoming insane. Journalists called the new fuel “loony gas.” In an interview of October 30, 1924, Midgley rubbed TEL on his hands to prove that small amounts were not toxic.
In the 1950s, as concern for the environment surfaced, new questions about automobile exhaust emission and air pollution arose. Eventually, the Environmental Protection Agency (EPA) proposed eliminating TEL in gasoline, mainly to prevent the lead from inactivating the platinum in the catalytic converters to be installed in all cars.
However, despite all its attendant problems, TEL did have a number of advantages. It removed the obstacle of knocking and ushered in an era of progress in transportation and petroleum technology. It enabled automotive engineers to increase the power and performance of engines and promoted the conservation of petroleum by increasing the efficiency of its use. TEL saved a third of the total gasoline costs that would have been paid if TEL had not been used.
CFCs
I remember the primitive ice boxes used to preserve perishable food, the daily placards we posted to notify the ice delivery person how much ice we needed that day, the daily inconvenience of ice replacement and the puddles of water from melting ice. Furthermore, inadequate refrigeration resulted in a number of cases of food poisoning.
Unlike Midgley’s discovery of TEL, which took more than five years, his discovery of the first CFC refrigerant, dichlorofluoromethane, required only three days. Although by 1930, the year I was born, the artificial refrigeration field was growing by leaps and bounds, the most common refrigerants—ammonia, methyl chloride or bromide, and sulfur dioxide—were toxic (resulting in deaths from refrigerator leaks), and the first three were also fire hazards.
One day in that year, Lester S. Keilholtz, chief engineer of the Frigidaire Division of General Motors, arrived in Dayton with a request from Kettering to Midgley to develop a nontoxic, nonflammable and inexpensive refrigerant.
Recalling his earlier success with TEL, Midgley again turned to the periodic table. He soon found that only the elements on the right-hand side of the table form sufficiently volatile compounds. He eliminated the volatile compounds of boron, silicon, phosphorus, arsenic, antimony, bismuth, tellurium and iodine as too toxic and unstable and the noble gases as too low in boiling point, and he focused on the remaining elements—carbon, nitrogen, oxygen, sulfur, hydrogen, fluorine, chlorine and bromine—from which every previous commercial refrigerant had been made.
Because flammability decreased from left to right and toxicity decreased within each periodic group from the heavier elements to the lighter elements, he selected fluorine as the most suitable candidate. Elemental fluorine was toxic, corrosive and the most reactive nonmetal, but no one had considered that some of its compounds might be nontoxic and nonreactive.
Midgley decided that dichlorofluoromethane would be the best choice. On January 8, 1937, he received the Society of Chemical Industry’s Perkin Medal for “distinguished work in applied chemistry, including the development of antiknock motor fuels and safe refrigerants.” With his flair for the dramatic, Midgley, ever the consummate showman, filled his lungs with the CFC vapor, exhaled it and extinguished a lighted candle, vividly proving both its nontoxicity and nonflammability.
CFCs are colorless, odorless, nonflammable, nontoxic substances, for which the low boiling points, low surface tension, low viscosity, insolubility in water and chemical inertness are remarkable. They have been widely used not only for refrigeration and air conditioning but also for aerosol spray propellants; foam for insulation, bedding and packing; and solvents and cleaners for the electronics industry. Also, halons, which contain bromine, provided the only safe method for extinguishing fires in areas such as computer installations and aircraft cockpits without harming people or equipment.
CFCs and the Ozone Layer
As with TEL, CFCs were a mixed blessing for Midgley and all of us. In 1970, atmospheric scientist James E. Lovelock used an electron capture detector to show that synthetic gases had spread globally throughout the atmosphere. He detected trichlorofluoromethane in the ambient air over Ireland, and in 1971 he found that it had spread through the surface over the north and south Atlantic Ocean.
After learning of Lovelock’s finding of CFCs in the troposphere, on October 1, 1973, F. Sherwood Rowland and Mario José Molina of the University of California, Irvine, began to search for a “sink,” that is, the reactions by which CFCs are decomposed and where the decomposition occurs. They discovered these insoluble substances could not be removed by rainfall and, because of their inertness, could not be removed by chemical reactions in the troposphere. Within three months, they calculated that continued use of CFCs would deplete the ozone layer by several percent after a few decades.
In an article in Nature (June 28, 1974), Molina and Rowland suggested that CFCs were destroying the ozone layer in the Earth’s stratosphere, a situation that has been described as a “planetary time bomb” and an “invisible menace.” In 1995, Molina and Rowland, together with Dutch scientist Paul Josef Crutzen, received the Nobel Prize in Chemistry “for their work in atmospheric chemistry, particularly concerning the formation and decomposition of ozone.” The award was widely viewed as a vindication of environmental science, long belittled by mainstream science.
Ironically, the inertness that made CFCs commercially useful allows them to remain in the atmosphere for 40–150 years. In the stratosphere, they are decomposed by exposure to ultraviolet light. In these catalytic chain reactions, one chlorine atom might destroy 100,000 molecules of ozone, creating an “ozone hole.”
This degradation of the Earth’s ozone layer, which shields our planet’s surface from the sun’s damaging ultraviolet radiation, has far-reaching environmental consequences, the most publicized and obvious of which is increasing cases of skin cancer (melanoma), cataracts and genetic damage. As the late Carl Sagan and others have warned, the extreme vulnerability to increased ultraviolet radiation of the phytoplankton—those tiny marine plants at the bottom of the ocean’s food chain—may ultimately threaten all life on Earth. CFCs are also implicated in causing deleterious effects on the global climate such as the greenhouse effect—the global warming that is endangering low-lying coastal regions with flooding on a grand scale.
Saving the Ozone Layer
In 1978, the EPA banned the use of CFCs in aerosol spray cans in the United States, and a number of chemical companies developed non-chlorine-containing replacements. American manufacturers contended that unilateral action would only place them at a disadvantage without protecting the atmospheric ozone layer and that any action to phase out CFCs must be an international one.
Global cooperation for protecting the ozone layer began with the Montréal Protocol, signed in 1987 by 24 governments and becoming effective in 1989. Containing provisions for the regular review of the adequacy of control measures based on assessments of evolving scientific, environmental, technical and economic information, it was ratified by 183 nations as of September 2002.
The depletion is caused mainly by the reaction of ozone with chlorine and bromine from industrially manufactured gases rather than by natural climatic variation. In the February 8, 1996, issue of Nature, James M. Russell III and colleagues at NASA’s Langley Research Center hammered the final nail in the coffin of the anti-environmentalists’ contentions, proving that human beings—not nature—are responsible for the chlorine that was destroying the ozone layer.
Nevertheless, the anti-environmental backlash, which Molina attributes to ignorance, will probably continue. According to Crutzen, anti-environmentalists “probably want a totally free society with no environmental laws whatsoever.”
The scientific data supporting the Montréal Protocol are voluminous, compelling and incontrovertible, but a number of governments, including our own, have moved to weaken its provisions, and the issue is still mired in controversy and politics.
Midgley’s Legacy
Was Midgley a saint or a sinner? History will eventually achieve a consensus on Midgley’s legacy. It reminds those prone to fault science and technology for the ills of modern life that these fields of human endeavor tend to be self-correcting activities.
