In 1774, Antoine Lavoisier established the conservation of mass as the keystone of chemical analysis.

The vacuum pump let scientists measure the weight of a gas that’s lighter than air which otherwise would lift, not weigh. Antoine Lavoisier showed water did not convert to earth by evaporation. He showed when phosphorus burned it gained in weight by combining with air. He thought that the additional weight after burning could be Joseph Black’s “fixed air,” that is, carbon dioxide. He and Joseph Priestley studied the gas from reducing the red calx of mercury which turned out to be oxygen. He worked with Pierre Simon Laplace to synthesize water from hydrogen and oxygen. Lavoisier carefully weighed reactants and products for each chemical reaction in sealed glass ampoules and found that the total mass was not changed.

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Lavoisier was not first to assume that mass is conserved in chemical reactions, but he established the general practice. Elements combine in measurable, whole-number proportions; for example, in water, there are two hydrogen for each oxygen.

See also in *The book of science:*

- 1774—
*Combustion*—Joseph Priestley, Carl Wilhelm Scheele, Antoine Lavoisier - 1784—
*Hydrogen and water*—Henry Cavendish - 1808—
*Atomic theory*—John Dalton - 1811,1909—
*Avogadro constant*—Amedeo Avogadro, Jean Baptiste Perrin - 1918—
*Noether’s theorem*—Emmy Noether

Readings in wikipedia:

]]>Priestley, Scheele, and Lavoisier separately discovered oxygen, although only Lavoisier was not bound by phlogiston theory in explaining combustion.

When Priestley discovered oxygen, he found it permitted things to burn longer than usual, so he thought oxygen must be air with its phlogiston removed. Made sense.

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*Phlogistón* is “burning up” in Greek.
Antoine Lavoisier named the inert part of air *azote* for
“lifeless” in Greek, but in English we call it
nitrogen. The Scottish physician Daniel Rutherford discovered
nitrogen in 1772, it was isolated first by Joseph Priestley in
1774, and it was named by the French chemist Jean-Antoine Chaptal
in 1790 because it was found in nitric acid,
“nitre-forming” in Greek.

See also in *The book of science:*

- Index of elements
- 1643—
*Atmospheric pressure*—Evangelista Torricelli, Blaise Pascal - 1661—
*Chymistry*—Robert Boyle - 1678—
*Hooke’s law*—Robert Hooke - 1774—
*Conservation of mass*—Antoine Lavoisier - 1774,1810—
*Chlorine*—Carl Wilhelm Scheele, Humphry Davy - 1784—
*Hydrogen and water*—Henry Cavendish - 1834—
*Laws of electrolysis*—Michael Faraday - 1863—
*Greenhouse effect*—John Tyndall - 1888—
*Nitrogen fixation*—Hermann Hellriegel - 1909—
*Ammonia*—Fritz Haber - 1937—
*Citric-acid cycle*—Hans Adolf Krebs

Readings in wikipedia:

]]>Barium: atomic number: 56; weight: 137.327; Alkaline earth metal; discovery: 1774,1808.

Heating witherite produced baryta, as Lavoisier called it, which is barium hydroxide, also called barote, or baryte, all from the Greek word meaningheavy.Carl Wilhelm Scheele recognized barium was a new heavy “earth” from testing small crystals of barium oxide he found in pyrolusite, a manganese mineral. Scheele wasn’t able to reduce his barium oxide to pure barium. Thirty-four years later, Humphry Davy isolated it using electrolysis and named the new metalbarium.

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poems* . . .

Carl Wilhelm Scheele discovered oxygen three years before Priestly,
but Priestley was first to publish.
Scheele discovered chlorine but misidentified it.
He *almost* isolated manganese,
and *almost* isolated barium.
Accumulated exposure to acids and heavy metals
contributed to his death at the age of 43.

See also in *The book of science:*

Readings in wikipedia:

]]>By 1796, John Whitehurst and Joseph-Michel Montgolfier invented and perfected the hydraulic ram pump.

Momentum of water whose flow, cyclically closed, rams water past a check valve up a hill, and regulates itself as the waste valve is first closed by the flow and then opened as it falls.

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Joseph-Michel Montgolfier and his brother Jacques-Étienne owned a paper mill in Voiron and developed the first manned untethered flight of a hot-air balloon. The balloon was made of paper. Joseph-Michel invented the first self-acting water ram to raise water at their paper mill. Early water rams cycled every minute or so, producing a loud thump with each cycle.

See also in *The book of science:*

- 1860—
*Roots blower*—Philander Roots, Francis Marion Roots - 1874—
*Rotary vane pump*—Charles C. Barnes - 1913—
*Tesla turbine*—Nikola Tesla

Readings in wikipedia:

]]>Nitrogen: atomic number: 7; weight: 14.007; Diatomic nonmetal; discovery: 1772.

Joseph Black called carbon dioxidefixed air.Daniel Rutherford was Joseph Black’s student. Rutherford removed the oxygen from air by having a mouse breathe it until it died then burning a candle and phosphorus in it until they wouldn’t burn then passing what remained through a solution to absorb thefixed airand he called the air that remainednoxious air.

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Humankind already has prescriptions and proscriptions for peace. Apparently, that’s not enough. Gradually, our activities have been poisoning our soil and water with nitrates and nitrites, which have damaging effects on our health.

See also in *The book of science:*

Readings in wikipedia:

]]>In 1771, Alexandre-Théophile Vandermonde was the first to analyze knots mathematically.

A cord may be wound around itself and after its two ends are fused together it will stay tied. The question arose as to how closed loops like this were to be related or distinguished. To Vandermonde, a knot was like the path of a knight in chess as it covers the board without repeating. To Lord Kelvin, an atom was a knot of aether tied to itself, which is both interesting and wrong. And this got Peter Guthrie Tait to classify all possible knots, at least up to ten crossings.

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At first evolving separately, knot theory eventually became part of topology, but I must say that it seems a lot more fun working knots than solving problems in topology.

See also in *The book of science:*

- 1736—
*Graph theory*—Leonhard Euler - 1736-1895—
*Topology*—Leonhard Euler, Antoine-Jean Lhuilier, August Ferdinand Möbius, Johann Benedict Listing, Henri Poincaré - 1758—
*Euler characteristic*—Leonhard Euler

Readings in wikipedia:

]]>Manganese: atomic number: 25; weight: 54.938044; Transition metal; discovery: 1770-1774.

Torbern Bergman investigated pyrolusite, a mineral containing manganese dioxide, distinguishing it from known elements including lime and magnesia alba, but was unable to isolate the element. His friend Carl Wilhelm Scheele used pyrolusite, as an oxydizing agent to produce chlorine and knew it contained a new element, giving it the namemaganese,but was also unable to isolate it. Johan Gottlieb Gahn, Bergman’s former assistant, was able to isolate the element from the mineral by reducing the dioxide with carbon to obtain this hard brittle silvery metal.

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poems* . . .

“Symptoms include apathy, bradykinesia, gait disorder with postural instability, and spastic-hypokinetic dysarthria.”

See also in *The book of science:*

Readings in wikipedia:

]]>In 1768, Johann Heinrich Lambert and Ferdinand von Lindemann proved that it is impossible to ”square the circle.”

The history of π (the ratio of the circumference to the diameter of a circle) is old. The Egyptians knew of it; the Babylonians knew of it; the Greek mathematician Archimedes used a polygon of ninety-six sides to calculate it; the Chinese mathematician Liu Hui knew of it and used polygons of one hundred ninety-two sides and three thousand seventy-two sides, calculating their areas rather than perimeters. Over the centuries, new methods for calculating π have resulted in increasing accuracy— but all decimal representations are approximations of a number that is never ending and never repeating.

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To “square the circle” is to find the length of the
sides of a square with the same area as a circle of a given
radius. The area of a circle of radius *r* is
π*r*^{2}, so success depends on the nature of π. The proofs of Lambert
and Lindemann mean that we know that it is impossible for anyone
to construct on a flat surface a square with the same area as a
given circle using a compass and ruler.

The expression “squaring the circle” means trying to do the impossible.

Archimedes used the “method of exhaustion” to approximate the value of π. The work of both Archimedes and Liu Hui prefigured calculus; Archimedes wrote of infinitesimals and Liu Hui described the use of the limit.

See also in *The book of science:*

- 260 BCE—
*Mechanical advantage*—Archimedes - 628—
*Zero*—Brahmagupta - 1202—
*Number system*—Leonardo Pisano Bigollo (Fibonacci) - 1656—
*Infinite and infinitesimal*—John Wallis - 1683—
*Euler’s number*—Jacob Bernoulli, Leonhard Euler - 1829—
*Non-Euclidean geometry*—Nicolai Lobachevsky, János Bolyai, Bernhard Riemann - 1931—
*Incompleteness theorems*—Kurt Gödel

Readings in wikipedia:

- “Pi”
- “Squaring the circle”
- “Irrational number”
- “Transcendental number”
- “Archimedes”
- “Method of exhaustion” used by Archimedes
- “Liu Hui”
- “Liu Hui’s π algorithm”
- “Calculus”
- “Limit (mathematics)”
- “Johann Heinrich Lambert”
- “Ferdinand von Lindemann”

In 1765, James Watt improved the steam engine, making it more efficient and more useful.

James Watt didn’t invent the steam engine; he improved the Newcomen engine. Newcomen didn’t invent it either; Newcomen combined a vacuum, created by cooling steam, from Thomas Savery, with a piston from Denis Papin. The Newcomen engine rocked a beam up and down, suitable for operating a pump.

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Atmospheric pressure was discovered in 1643 by Evangelista
Torricelli, who invented the mercury barometer. Blaise Pascal was
able to prove that the gap at the end of the barameter was a
vacuum. Newcomen’s engine was called an *atmospheric
engine* because it relied on atmospheric pressure against a vacuum
created by cooling steam in a chamber. The Newcomen engine was not
driven by steam pressure.

See also in *The book of science:*

- 70—
*Windmill*—Hero of Alexandria (Heron) - 1643—
*Atmospheric pressure*—Evangelista Torricelli, Blaise Pascal - 1678-1876—
*Internal combustion engine*—Jean de Hautefeuille, Christiaan Huygens, Denis Papin, François Isaac de Rivaz, Nicéphore Niépce, Claude Niépce, Samuel Brown, William Barnett, Eugenio Barsanti, Felice Matteucci, Étienne Lenoir, Alphonse Beau de Rochas, Nikolaus Otto, Eugen Langen - 1761—
*Latent heat*—Joseph Black - 1805—
*Oruktor Amphibolos*—Oliver Evans - 1816—
*Stirling engine*—Robert Stirling - 1847—
*Laws of thermodynamics*—Benjamin Thompson, Nicolas Léonard Sadi Carnot, James Prescott Joule, Rudolf Clausius - 1871—
*Wind tunnel*—Francis Herbert Wenham - 1885—
*Automobile*—Karl Benz - 1893—
*Diesel engine*—Rudolf Diesel - 1903—
*Airplane*—Wilbur Wright, Orville Wright - 1913—
*Tesla turbine*—Nikola Tesla

Readings in wikipedia:

]]>In 1765, Lazzaro Spallanzani disproved the theory of spontaneous generation. He pasteurized and sealed his samples to prove that microbes cannot grow without the introduction of air that carries microbial endospores.

Maggots grow in cow pies. Tapeworms grow in intestines. Without knowing that flies and worms lay eggs and that stepping barefoot into feces or eating undercooked food can pick them up, people believed that very small creatures were generated spontaneously from decaying plant and animal matter. People like John Needham asserted that a vital principle inhered in such substances that spontaneously generated living things. Lazzaro Spallanzani tried to prove this, sterilizing his samples in sealed flasks, and failed. Realizing that heating and sealing his samples killed anything alive that was already in them and protected them from contamination, Spallanzani demonstrated the principle of pasteurization and scooped Louis Pasteur by ninety-five years.

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Worms have been found in rocks at the bottom of a diamond mine; bacteria has been found deep in volcanic rock.

The theory of spontaneous generation originated with Aristotle, who wrote that the “vital heat” contained in air and water was responsible. Needham exposed his broths to air as they cooled after boiling (insufficiently to kill microbial endospores in the broths), not imagining that air could contain microbes and microbial endospores responsible for what he thought were generated spontaneously.

Apes and chimpanzees have been found to “self-medicate” by eating particular astringent leaves and inner barks to cure themselves of malaria and worms.

See also in *The book of science:*

- 1628—
*Circulation of the blood*—William Harvey - 1668—
*Parasites*—Francesco Redi - 1669—
*Epigenesis*—Jan Swammerdam - 1673—
*Microorganisms*—Robert Hooke, Antonie van Leeuwenhock - 1796—
*Vaccination*—Edward Jenner - 1828—
*Synthesis of urea*—Friedrich Wöhler - 1854—
*Cholera and the pump*—John Snow - 1858—
*Communities of cells*—Rudolf Virchow (cell theory) - 1878—
*Germ theory*—Louis Pasteur - 1953—
*Abiogenesis*—Stanley Miller, Harold Urey

Readings in wikipedia:

]]>In 1763, Thomas Bayes introduced the need to use the base rate in determining a probability.

Intuition disregards the base rate; Bayes taught us to regard it. If you think about whether a mammogram detects breast cancer, you must consider the base rate— the prevalence of breast cancer. If a mammogram shows you have breast cancer and the diagnosis is accurate only 80 percent of the time but only one person in a hundred gets breast cancer, then your chance of having it is only about 7.8 percent.

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It goes by the name of “logic,” but what we mean is trying to overcome our instinctual thought-processes to adhere more closely to reality.

See also in *The book of science:*

Readings in wikipedia:

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