January 6 marks the passing of Étienne François Geoffroy. Geoffroy was the French physician best known for compiling the first chemical affinity tables.
Chemists have long known if you mix two substances together, sometimes you get something new. The substances that do form new products are said to share an affinity towards each other. Geoffroy made systematic tests of acting substances on one another and recording the results. He then published tables of substances and the things that share an affinity with them.
This is an example of one of Geoffroy’s tables taken from the 1718 book Memoires de l’Academie Royale des Sciences.
The top of the table is the substance. Everything underneath in the vertical column is a substance that shares an affinity with the top row substance.
Geoffroy’s tables of chemical affinity were the beginning of understanding chemical bonding. Today, chemical affinity refers to the tendency of atoms to form bonds with other atoms and compounds.
Notable Science History Events for January 6
1990 – Pavel Alekseyevich Cherenkov died.
Cherenkov was a Soviet physicist who shares the 1958 Nobel Prize in Physics with Igor Yevgenyevich Tamm and Il´ja Mikhailovich Frank for their discovery and description of the Cherenkov effect. The Cherenkov effect occurs when a particle passes through a medium at a speed greater than the speed of light in that medium. This causes a distinctive blue glow that is commonly seen in the water around nuclear reactors.
1945 – Vladimir Ivanovich Vernadsky died.
Vernadsky was a Russian geologist who was one of the founders of the study of geochemistry. He studied the elemental distribution of the Earth’s crust and electrical and magnetic, thermal, and optical properties of crystals. He was also known for popularizing the idea of the noosphere, or sphere of human thought. He noted the great effect humans have on the geology of their environment and included this in a wider understanding of biospheres.
1944 – Rolf Martin Zinkernagel was born.
Zinkernagel is a Swiss immunologist who shares the 1996 Nobel Prize in Medicine with Peter C. Doherty 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) proteins. If the T cell discovers these molecules, it kills the cell so the infection cannot reproduce.
1884 – Gregor Johann Mendel died.
Mendel was an Austrian priest and scientist who studied the inheritance of traits in pea plants from generation to generation. The laws of inheritance that he discovered became the basis for the study of classical genetics.
1833 – Fausto D’Elhuyar died.
Biblioteca Nacional de España
Fausto D’Elhuyar was a Spanish mineralogist who, together with his brother Juan José D’Elhuyar, isolated the element tungsten from wolfram ore. Carl Scheele had discovered tungsten two years earlier in the form of tungstic acid but did not separate the tungsten metal from the acid. The D’Elhuyar brothers reduced the acid through charcoal and removed the metal.
1800 – William Brownrigg died.
Brownigg was an English physician and scientist who identified platinum as an element. He received samples from a relative in Jamaica and identified the unique nature of the metal.
1795 – Anselme Payen was born.
Payen was a French chemist who was the first to isolate and discover the first enzyme diastase. Diastase is a hydrolase enzyme that breaks down carbohydrates. He was also the first to discover and name cellulose. Cellulose is the basic component of green plant cells. Payen discovered a method to industrially produce borax from boric acid and broke the Dutch monopoly on mined borax.