February 24th marks the passing of Henry Cavendish. Cavendish was a British natural philosopher that made meticulous studies of gases. He made extensive studies of the 'airs' he collected including the discovery of hydrogen. He collected hydrogen by collecting the gas given off by the reaction of metals and strong acids and called it 'inflammable air'. Inflammable air was almost entirely made up of phlogiston, the substance in a body that causes them to burn. He found if he combined three parts inflammable air with seven parts of common air and dropped fire into the mixture, it would make a very loud noise and produce water. He also noted that all of the inflammable air and nearly a fifth of the common air was used up in this experiment. Further investigation found if he mixed two parts of inflammable air with one part dephlogisticated air (oxygen) would produce water. We know this reaction today as:
2 H2 (g) + O2 (g) → H2O (l)
He also determined an accurate composition of the atmosphere where he found 79.167% was phlogisticated air (nitrogen mostly) and 20.833% dephlogistacted air (oxygen). He went on to question whether phlogisticated air was made up of many different airs.
We now know that common air is made up of many elements and compounds. Find out what the difference between the words "flammable" vs "inflammable" mean and else occurred on this day in science history.
1923 - Edward Williams Morley died
Morley attempted with A. A. Michelson to detect the 'aether' in the Michelson/Morley experiment. The null results of this experiment would eventually lead to Einstein's theory of relativity.
1841 - Carl Gräbe was born.
Gräbe (or Graebe) was a German organic chemist who synthesized the dye alizarin with Carl Liebermann. This discovery would lead to and push the German dye and pigment industry to prominence. Gräbe also introduced the nomenclature 'para', 'meta' and 'ortho' to describe the position of groups where they attach to benzene rings.
1811 - Eugène Melchior Péligot was born.
Péligot was a French chemist who first isolated the element uranium. He produced the metal sample by heating a salt of uranium with potassium. He also discovered the methyl radical with Jean-Baptiste Dumas while experimenting with methanol.
1810 - Henry Cavendish died
Cavendish was a British natural philosopher who discovered "inflammable air" or the element hydrogen. He also discovered it produced water when combusted. Cavendish is also known for the Cavendish experiment to determine the gravitational constant and density of the Earth.
1799 - Georg Christoph Lichtenberg died.
Lichtenberg was a German scientist who's main research was with electricity. He discovered when a static charge is introduced to a dielectric, interesting branching patters appear. These patterns are called Lichtenberg figures.
1664 - Thomas Newcomen was born.
Newcomen was an English ironmonger who constructed the first practical atmospheric steam engine pump to remove water from coal mines. The Newcomen steam engine marks the beginning of the Industrial Revolution.
1582 - The Gregorian calendar was created.
The current calendar was created by Pope Gregory XIII. He reformed the previous Julian calendar to its current form by papal bull. The modified calendar introduced a leap day every four years and the date format would include a year, month and day number.
Wednesday, February 24, 2010
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