Knock was a destructive phenomenon that occurred in internal combustion engines and only became worse at high engine-compression ratios. Because higher compression ratios were necessary to improve engine power and fuel efficiency, and as a post-World War I fuel shortage was expected, this problem was top priority.Midgley soon uncovered that contrary to popular belief, knock was the result of a fuel failure, not an engine failure. A trial and error search commenced to find a fuel additive that would reduce the temperature and pressure within the cylinder to suppress the knock. In December 1921, an engine test was run with a small amount of tetraethyl lead, completely eliminating knock. This discovery enabled airplane makers to develop more powerful engines, which gave the U.S. a decisive advantage during the Second World War. The increased engine horsepower also allowed for greater aircraft safety, reliability and speed.
In 1930, Midgley was charged to find an inexpensive, nontoxic refrigerant for use in household appliances for General Motors, and thus discovered Freon. It wasn't until the 1970's that lead pollution concerns resulted in a ban on lead compounds in gasoline and the introduction of less toxic anti-knock additives.
A second-generation inventor, Midgley was born in 1889 in Beaver Falls, Pennsylvania and grew up in Columbus, Ohio. Determined to follow in his father's footsteps as an inventor, Midgley graduated from Cornell University in 1911 with a degree in mechanical engineering. That same year, he married Carrie May Reynolds and later had two children. He died in 1944 at the age of 55 in Worthington, Ohio.
Midgley's work earned him four major awards from the American Chemical Society including the Nichols Medal in 1922, the Perkins Medal in 1937, the Priestley Medal in 1941 and the William Gibbs Medal in 1942. He was also awarded two honorary degrees, elected to the National Academy of Sciences, served as president and chairman of the American Chemical Society in 1944 and held over 100 patents in the course of his career.