1920 - George Porter was born.Porter was an British chemist who shares half the 1967 Nobel Prize in Chemistry with Ronald Norrish for their research into very fast chemical reactions. They used pulses of light to increase the number of free radicals in some organic compounds to determine the intermediate steps to perform these reactions.
1900 - George Eugene Uhlenbeck was born.Uhlenbeck was a Dutch-American physicist who proposed the idea of electron spin with Samuel Abraham. Electron spin is the fourth quantum number and describes an intrinsic angular momentum of an electron. Spin can have one of two values, typically called spin up or spin down. He is also known for the Ornstein-Uhlenbeck process that describes Brownian motion in a fluid with friction.
1893 - Johann Rudolf Wolf died.
Wolf was a Swiss astronomer who discovered the sun spot cycle discovered by Heinrich Schwabe had a period of 11.1 years and was linked to geomagnetic activity on Earth. During his research, he developed a method of measuring the activity of sunspots known as the Wolf sunspot number that is in use today.
1863 - Charles Martin Hall was born.
Hall was an American chemist who discovered an inexpensive method to refine aluminum from ore. He built an apparatus that passed an alternating electrical current through a solution of alumina and cryolite that would cause aluminum metal to precipitate out. This process was also discovered by French chemist, Paul-Louis-Toussaint Héroult at nearly the same time and is generally known as the Hall-Héroult process. It was responsible for greatly reducing the cost to produce aluminum and made it one of the most widely used metals today.