2000 - Konrad Bloch died.

Bloch was a German-American biochemist who shared the 1964 Nobel Prize in Medicine with Feodor Lynen for their discoveries concerning the biosynthesis of fatty acids and cholesterol. Bloch discovered that acetic acid was a major contributor to the natural formation of cholesterol. Both men discovered how the body creates and regulates fatty acids and cholesterol.

1940 - Peter Charles Doherty was born.

Doherty is an Australian veterinarian surgeon who shares the 1996 Nobel Prize in Medicine with Rolf Zinkernagel for their discoveries in cell based immune defense. They discovered how T cells recognize infected cells. They found T-cells seek out two molecules on the surface of an infected cell, the virus infecting the cell and major histocompatibility complex (MHC) protiens. If the T cell discovers these molecules, it kills the cell so the infection cannot reproduce.

1930 - Herbert Henry Dow died.

Dow was an Canadian-American chemist who discovered a process to cheaply remove bromine from natural brine solutions. He began a business to market this process and produce inexpensive bromine for industry that started an international trade war. The result of the dispute would enrich Dow and turn his business into what would become Dow Chemical Company, the third largest chemical company in the world.

1915 - Theodor Heinrich Boveri died.

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Boveri was a German cytologist who showed chromosomes are separate, continuous entities within the nucleus of a cell and one chromosome is responsible for certain hereditary traits and the importance of cytoplasm. He also theorized, with Edouard van Beneden, that the egg and sperm cells contribute an equal number of chromosomes to the new cell created during fertilization. Boveri introduced the term centrosome to describe the division center for a cell during cell division.

1910 - Torbjörn Oskar Caspersson was born.

Caspersson was a Danish cytologist who was the first to use an ultraviolet microscope to identify nucleic acid content in cells. He also discovered the quinacrine mustard stain that caused chromosomes to show light and dark bands along their length to quickly identify all 22 autosomes and XY chromosomes.

1858 - Carl Gustaf Mosander died.

Mosander was a Swedish chemist who discovered the firstlanthanides. He was investigating rare earth minerals and discovered the elements lanthanum, terbium, and erbium. He also believed he discovered another element he named didyium. Didyium was later determined to not be an element but a mixture of the elementspraseodymium and neodymium.

1829 - Asaph Hall III was born.

US Navy

Hall was an American astronomer who discovered the two moons of Mars, Phobos and Deimos. He worked for the US Naval Observatory and determined the orbits of several planet's satellites and the rotation rate of Saturn.

1608 - Evangelista Torricelli was born.

Torricelli was an Italian physicist who invented the mercury barometer. He was working on a method to use mercury as a pump and filled a tube of mercury with mercury and sealed one end. The other end was submerged into a basin of mercury. The mercury level in the tube dropped down and created a vacuum in the sealed end. He later discovered the level would change as atmospheric pressure changed. The non-SI pressure unit Torr was named in his honor.