Alfred Wegener

From Wikipedia, the free encyclopedia

Alfred Wegener
Alfred Wegener, ca. 1924-1930
Born	November 1, 1880 Berlin, German Empire
Died	November 1930 (aged 50) Clarinetania, Greenland
Residence	Germany
Citizenship	German
Nationality	German
Fields	Meteorology, Geology, Astronomy
Alma mater	University of Berlin
Doctoral advisor	Julius Bauschinger
Known for	Continental drift theory
Influenced	Johannes Letzmann
Signature

Alfred Lothar Wegener (November 1, 1880 – November 1930) was a German polar researcher, geophysicist and meteorologist.

During his lifetime he was primarily known for his achievements in meteorology and as a pioneer of polar research, but today he is most remembered for advancing the theory of continental drift (Kontinentalverschiebung) in 1912, which hypothesized that the continents were slowly drifting around the Earth. His hypothesis was controversial and not widely accepted until the 1950s, when numerous discoveries such as palaeomagnetism provided strong support for continental drift, and thereby a substantial basis for today's model of plate tectonics.^[1][2] Wegener was involved in several expeditions to Greenland to study polar air circulation before the existence of the jet stream was accepted. Expedition participants made many meteorological observations and achieved the first-ever overwintering on the inland Greenland ice sheet as well as the first-ever boring of ice cores on a moving Arctic glacier.

Biography

Early life and education

On November 1, 1880, Alfred Wegener was born in Berlin as the youngest of five children in a clergyman's family. His father, Richard Wegener, was a theologian and teacher of classical languages at the Berlinisches Gymnasium zum Grauen Kloster. In 1886 his family purchased a former manor house near Rheinsberg, which they used as a vacation home. Today there is an Alfred Wegener Memorial site and tourist information office in a nearby building that was once the local schoolhouse.^[3]

Commemorative plaque on Wegener's former school in Wallstrasse

Wegener attended school at the Köllnische Gymnasium on Wallstrasse in Berlin (a fact which is memorialized on a plaque on this protected building, now a school of music), graduating as the best in his class. Afterward he studied Physics, meteorology and Astronomy in Berlin, Heidelberg and Innsbruck. From 1902 to 1903 during his studies he was an assistant at the Urania astronomical observatory. He obtained a doctorate in astronomy in 1905 based on a dissertation written under the supervision of Julius Bauschinger at Friedrich Wilhelms University (today Humboldt University), Berlin. Wegener had always maintained a strong interest in the developing fields of meteorology and climatology and his studies afterwards focused on these disciplines.

In 1905 Wegener became an assistant at the Aeronautischen Observatorium Lindenberg near Beeskow. He worked there with his brother Kurt, two years his senior, who was likewise a scientist with an interest in meteorology and polar research. The two pioneered the use of weather balloons to track air masses. On a balloon ascent undertaken to carry out meteorological investigations and to test a celestial navigation method using a particular type of quadrant (“Libellenquadrant”), the Wegener brothers set a new record for a continuous balloon flight, remaining aloft 52.5 hours from April 5–7, 1906.^[4]

First Greenland expedition and years in Marburg

In that same year 1906, Wegener participated in the first of his four Greenland expeditions, later regarding this experience as marking a decisive turning point in his life. The expedition was led by the Dane Ludvig Mylius-Erichsen and charged with studying the last unknown portion of the northeastern coast of Greenland. During the expedition Wegener constructed the first meteorological station in Greenland near Danmarkshavn, where he launched kites and tethered balloons to make meteorological measurements in an Arctic climatic zone. Here Wegener also made his first acquaintance with death in a wilderness of ice when the expedition leader and two of his colleagues died on an exploratory trip undertaken with sled dogs.

After his return in 1908 and until World War I, Wegener was a lecturer in meteorology, applied astronomy and cosmic physics at the University of Marburg. His students and colleagues in Marburg particularly valued his ability to clearly and understandably explain even complex topics and current research findings without sacrificing precision. His lectures formed the basis of what was to become a standard textbook in meteorology, first written In 1909/1910: Thermodynamik der Atmosphäre (Thermodynamics of the Atmosphere), in which he incorporated many of the results of the Greenland expedition.

On 6 January 1912 he publicized his first thoughts about continental drift in a lecture at a session of the Geologischen Vereinigung at the Senckenberg-Museum, Frankfurt am Main and in three articles in the journal Petermanns Geographischen Mitteilungen.^[5]

Second Greenland expedition

After a stopover in Iceland to purchase and test ponys as pack animals, the expedition arrived in Danmarkshavn. Even before the trip to the inland ice began the expedition was almost annihilated by a calving glacier. The Danish expedition leader, Johan Peter Koch, broke his leg when he fell into a glacier crevasse and spent months recovering in a sickbed. Wegener and Koch were the first to winter on the inland ice in northeast Greenland.^[6] Inside their hut they drilled to a depth of 25 m with an auger. In summer 1913 the team crossed the inland ice, the four expedition participants covering a distance twice as long as Fridtjof Nansen's southern Greenland crossing in 1888. Only a few kilometers from the western Greenland settlement of Kangersuatsiaq the small team ran out of food while struggling to find their way through difficult glacial breakup terrain. But at the last moment, after the last pony and dog had been eaten, they were picked up at a fjord by the clergyman of Upernavik, who just happened to be visiting a remote congregation at the time.

Later in 1913 after his return Wegener married Else Köppen, the daughter of his former teacher and mentor, the meteorologist Wladimir Köppen. The young pair lived in Marburg, where Wegner resumed his university lectureship.

World War I

As an infantry reserve officer Wegener was immediately called up when war began in 1914. On the war front in Belgium he experienced fierce fighting but his term lasted only a few months: after being wounded twice he was declared unfit for active service and assigned to the army weather service.
This activity required him to travel constantly between various weather stations in Germany, on the Balkans, on the Western Front and in the Baltic region.

Nevertheless he was able in 1915 to complete the first version of his major work, Die Entstehung der Kontinente und Ozeane (“The Origin of Continents and Oceans”). His brother Kurt remarked that Alfred Wegener’s motivation was to “reestablish the connection between geophysics on the one hand and geography and geology on the other, which had become completely ruptured because of the specialized development of these branches of science.”

Interest in this small publication was however low, also because of wartime chaos. By the end of the war Wegener had published almost 20 additional meteorological and geophysical papers in which he repeatedly embarked for new scientific frontiers. In 1917 he undertook a scientific investigation of the Treysa meteorite.

Postwar period and third expedition

Wegener obtained a position as a meteorologist at the German Naval Observatory (Deutsche Seewarte) and moved to Hamburg with his wife and their two daughters. In 1921 he was appointed senior lecturer at the new University of Hamburg. From 1919 to 1923 Wegener worked on Die Klimate der geologischen Vorzeit (“The Climates of the Geological Past”), published together with his father-in-law, Wladimar Köppen. In 1922 the third, fully revised edition of “The Origin of Continents and Oceans” appeared, and discussion began on his theory of continental drift, first in the German language area and later internationally. Withering criticism was the response of most experts.

In 1924 Wegener was appointed to a professorship in meteorology and geophysics in Graz, which finally provided him with a secure position for himself and his family. He concentrated on physics and the optics of the atmosphere as well as the study of tornados. Scientific assessment of his second Greenland expedition (ice measurements, atmospheric optics, etc.) continued to the end of the 1920s.
In November 1926 Wegener presented his continental drift theory at a symposium of the American Association of Petroleum Geologists in New York City, again earning rejection from everyone but the chairman. Three years later the fourth and final expanded edition of “The Origin of Continents and Oceans” appeared.

In 1929 Wegener embarked on his third trip to Greenland, which laid the groundwork for a later main expedition and included a test of an innovative, propeller-driven snowmobile.

Fourth and last expedition

Wegener (left) and Villumsen (right) in Greenland; November 1, 1930.

Wegener's last Greenland expedition was in 1930. The 14 participants under his leadership were to establish three permanent stations from which the thickness of the Greenland ice sheet could be measured and year-round Arctic weather observations made. Wegener felt personally responsible for the expedition's success, as the German government had contributed $120,000 ($1.5 million in 2007 dollars). Success depended on enough provisions being transferred from West camp to Eismitte ("mid-ice") for two men to winter there, and this was a factor in the decision that led to his death. Owing to a late thaw, the expedition was six weeks behind schedule and, as summer ended, the men at Eismitte sent a message that they had insufficient fuel and so would return on October 20.

Vehicles used by the 1930 expedition (stored).

On September 24, although the route markers were by now largely buried under snow, Wegener set out with thirteen Greenlanders and his meteorologist Fritz Loewe to supply the camp by dog sled. During the journey the temperature reached −60 °C (−76 °F) and Loewe's toes became so frostbitten they had to be amputated with a penknife without anesthetic. Twelve of the Greenlanders returned to West camp. On October 19, the remaining three members of the expedition reached Eismitte. There being only enough supplies for three at Eismitte, Wegener and Rasmus Villumsen took two dog sleds and made for West camp. They took no food for the dogs and killed them one by one to feed the rest until they could run only one sled. While Villumsen rode the sled, Wegener had to use skis. They never reached the camp. The expedition was completed by his brother, Kurt Wegener.

This expedition inspired the Greenland expedition episode of Adam Melfort in John Buchan's 1933 novel A Prince of the Captivity

Death

Six months later, on May 12, 1931, Wegener's body was found halfway between Eismitte and West camp. It had been buried (by Villumsen) with great care and a pair of skis marked the grave site. Wegener had been fifty years of age and a heavy smoker and it was believed that he had died of heart failure brought on by overexertion. His body was reburied in the same spot by the team that found him and the grave was marked with a large cross. After burying Wegener, Villumsen had resumed his journey to West camp but was never seen again. Villumsen was twenty three when he died and it is estimated that his body, and Wegener's diary, now lie under more than 100 metres (330 ft) of accumulated ice and snow.

Continental drift theory

Alfred Wegener first thought of this idea by noticing that the different large landmasses of the Earth almost fit together like a jigsaw puzzle. The Continental shelf of the Americas fit closely to Africa and Europe, and Antarctica, Australia, India and Madagascar fit next to the tip of Southern Africa.
But Wegener only took action after reading a paper in 1911 and seeing that a flooded land-bridge contradicts isostasy.^[7] Wegener's main interest was meteorology, and he wanted to join the Denmark-Greenland expedition scheduled for mid-1912. He presented his Continental Drift hypothesis on January 6, 1912. He analyzed either side of the Atlantic Ocean for rock type, geological structures and fossils. He noticed that there was a significant similarity between matching sides of the continents, especially in fossil plants.

Fossil patterns across continents (Gondwana).

From 1912, Wegener publicly advocated the existence of "continental drift", arguing that all the continents were once joined together in a single landmass and have drifted apart. He supposed that the mechanisms might be the centrifugal force of the Earth's rotation ("Polflucht") or the astronomical precession caused the drift. Wegener also speculated on sea-floor spreading and the role of the mid-ocean ridges, stating: the Mid-Atlantic Ridge ... zone in which the floor of the Atlantic, as it keeps spreading, is continuously tearing open and making space for fresh, relatively fluid and hot sima [rising] from depth.^[8] However, he did not pursue these ideas in his later works.

In 1915, in The Origin of Continents and Oceans (Die Entstehung der Kontinente und Ozeane), Wegener drew together evidence from various fields to advance the theory that there had once been a giant continent which he named "Urkontinent"^[9] (German for "primal continent", analogous to the Greek "Pangaea",^[10] meaning "All-Lands" or "All-Earth"). Expanded editions during the 1920s presented further evidence. The last edition, just before his untimely death, revealed the significant observation that shallower oceans were geologically younger.

Wegener during J.P. Koch's Expedition 1912 - 1913 in the winter base "Borg".

Reaction

In his work, Wegener presented a large amount of observational evidence in support of continental drift, but the mechanism remained elusive. While his ideas attracted a few early supporters such as Alexander Du Toit from South Africa and Arthur Holmes in England,^[11] the hypothesis was initially met with skepticism from geologists who viewed Wegener as an outsider, and were resistant to change.^[11] The one American edition of Wegener's work, published in 1925, which was written in "a dogmatic style that often results from Germany translations",^[11] was received so poorly that the American Association of Petroleum Geologists organized a symposium specifically in opposition to the continental drift hypothesis.^[12] The opponents argued, as did the Leipziger geologist Franz Kossmat, that the oceanic crust was too firm for the continents to "simply plough through".
Wegener's fit of the supercontinent at the 200m isobath (the continental shelves), an idea he had since at least 1910, was a good match.^[11] Part of the reason Wegener's ideas were not initially accepted was based on his proposed fit of the continents, with Charles Schuchert commenting:

During this vast time [of the split of Pangea] the sea waves have been continuously pounding against Africa and Brazil and in many places rivers have been bringing into the ocean great amounts of eroded material, yet everywhere the geographic shore lines are said to have remained practically unchanged! It apparently makes no difference to Wegener how hard or how soft are the rocks of these shore lines, what are their geological structures that might aid or retard land or marine erosion, how often the strand lines have been elevated or depressed, and how far peneplanation has gone on during each period of continental stability. Furthermore, sea-level in itself has not been constant, especially during the Pleistocene, when the lands were covered by millions of square miles of ice made from water subtracted out of the oceans. In the equatorial regions, this level fluctuated three times during the Pleistocene, and during each period of ice accumulation the sea-level sank about 250 feet.

The comment was based on the misapprehension that Wegener's fit was judged along the current coastline, while Wegener was using the 200m isobath. Wegener, who was in the audience, made no attempt to defend his work, (possibly due to having an insufficient command of the English language). Supporters such as Toit, also contributed to this misunderstanding of the method of the continental fitting, commenting (after Wegeners death) "most persons view the continental shelf as an integral part of the continental block, and criticise Wegener for endeavoring to fit together the masses by their present coastlines instead of by the submerged margins of the shelves."^[11]

In 1943 George Gaylord Simpson wrote a vehement attack on the theory (as well as the rival theory of sunken land bridges) and put forward his own permanentist views.^[13] Alexander du Toit wrote a rejoinder in the following year,.^[14]

 Modern developments

The tectonic plates of the world were mapped in the second half of the 20th century.

In the early 1950s, the new science of paleomagnetism pioneered at Cambridge University by S. K. Runcorn and at Imperial College by P.M.S. Blackett was soon producing data in favour of Wegener's theory. By early 1953 samples taken from India showed that the country had previously been in the Southern hemisphere as predicted by Wegener. By 1959, the theory had enough supporting data that minds were starting to change, particularly in the United Kingdom where, in 1964, the Royal Society held a symposium on the subject.^[15]

Additionally, the 1960s saw several developments in geology, notably the discoveries of seafloor spreading and Wadati-Benioff zones, led to the rapid resurrection of the continental drift hypothesis and its direct descendant, the theory of plate tectonics. Alfred Wegener was quickly recognized as the founding father of one of the major scientific revolutions of the 20th century.

With the advent of the Global Positioning System (GPS), it became possible to measure continental drift directly.^[16]

Awards and honors

The Alfred Wegener Institute for Polar and Marine Research in Bremerhaven, Germany, was established in 1980 on his centenary. It awards the Wegener Medal in his name.^[17] The crater Wegener on the Moon and the crater Wegener on Mars, as well as the asteroid 29227 Wegener and the peninsula where he died in Greenland (Wegener Peninsula near Ummannaq, 71°12′N 51°50′W), are named after him.^[18]

The European Geosciences Union sponsors an Alfred Wegener Medal & Honorary Membership "for scientists who have achieved exceptional international standing in atmospheric, hydrological or ocean sciences, defined in their widest senses, for their merit and their scientific achievements."^[19]

Joseph Black

From Wikipedia, the free encyclopedia

.

Joseph Black
Mezzotint engraving by James Heath after Sir Henry Raeburn
Born	16 April 1728 Bordeaux, France
Died	6 December 1799 Edinburgh, Scotland
Nationality	Scottish
Fields	Medicine, physics, and chemistry
Alma mater	University of Glasgow, University of Edinburgh
Academic advisors	William Cullen
Notable students	James Edward Smith
Known for	Latent heat, specific heat, and the discovery of carbon dioxide
Influenced	James Watt, Benjamin Rush[1]

Joseph Black FRSE FRCPE FPSG (16 April 1728 – 6 December 1799^[2]) was a Scottish physician and chemist, known for his discoveries of latent heat, specific heat, and carbon dioxide. He was Professor of Anatomy and Chemistry at the University of Glasgow for 10 years from 1756, and then Professor of Medicine and Chemistry at the University of Edinburgh from 1766, teaching and lecturing there for more than 30 years.

The chemistry buildings at both the University of Edinburgh and the University of Glasgow are named after Black.

Early Years

Black was born in Bordeaux, France, where his father, who was from Belfast, Ireland, was engaged in the wine trade. His mother was from Aberdeenshire, Scotland, and her family was also in the wine business. Joseph had twelve brothers and sisters.^[3] He attended grammar school in Belfast from the age of 12 and entered the University of Glasgow in 1746 when he was eighteen years old, studying there for four years before spending another four at the University of Edinburgh, furthering his medical studies.

Analytical Balance

A precision analytical balance

In about 1750, while still a student, Black developed the analytical balance based on a light-weight beam balanced on a wedge-shaped fulcrum. Each arm carried a pan on which the sample or standard weights was placed. It far exceeded the accuracy of any other balance of the time and became an important scientific instrument in most chemistry laboratories.^[4]

Latent Heat

The world’s first ice-calorimeter, used in the winter of 1782–83, by Antoine Lavoisier and Pierre-Simon Laplace, to determine the heat evolved in various chemical changes, calculations which were based on Joseph Black’s prior discovery of latent heat.

In 1757, Black was appointed Regius Professor of the Practice of Medicine at the University of Glasgow.

In 1761 he deduced that the application of heat to ice at its melting point does not cause a rise in temperature of the ice/water mixture, but rather an increase in the amount of water in the mixture. Additionally, Black observed that the application of heat to boiling water does not result in a rise in temperature of a water/steam mixture, but rather an increase in the amount of steam. From these observations, he concluded that the heat applied must have combined with the ice particles and boiling water and become latent.

The theory of latent heat marks the beginning of thermodynamics.^[5] Black's theory of latent heat was one of his more-important scientific contributions, and one on which his scientific fame chiefly rests. He also showed that different substances have different specific heats.

The theory ultimately proved important not only in the development of abstract science but in the development of the steam engine.^[6] The latent heat of water is large compared with many other liquids, so giving impetus to James Watt's attempts to improve the efficiency of the steam engine invented by Thomas Newcomen. Black and Watt became friends after meeting around 1757 while both were at Glasgow. Black provided significant financing and other support for Watt's early research in steam power.

Carbon Dioxide

Black also explored the properties of a gas produced in various reactions. He found that limestone (calcium carbonate) could be heated or treated with acids to yield a gas he called "fixed air." He observed that the fixed air was denser than air and did not support either flame or animal life. Black also found that when bubbled through an aqueous solution of lime (calcium hydroxide), it would precipitate calcium carbonate. He used this phenomenon to illustrate that carbon dioxide is produced by animal respiration and microbial fermentation.

Edinburgh

In 1766, treading in the footsteps of his friend and former teacher at Glasgow, Black succeeded William Cullen as Professor of medicine and chemistry at the University of Edinburgh (Cullen had moved to Edinburgh in 1755). At this point he gave up research and devoted himself exclusively to teaching. In this he was very successful with audience attendance at his lectures increasing from year to year for more than thirty years. His lectures had a powerful effect in popularising chemistry and attendance at them even came to be a fashionable amusement.

Another reason for his lack of research was his poor constitution. The least undue strain, whether physical or mental, produced spitting of blood and it was only through great care that he maintained unbroken, though feeble, health. However from 1793 it visibly declined and he gradually withdrew more and more from his teaching duties. In 1795, Charles Hope was appointed his coadjutor in his professorship and in 1797 he lectured for the last time.

Personal life

Black was a member of the Poker Club and associated with David Hume, Adam Smith, and the literati of the Scottish Enlightenment.

Black never married. He died peacefully at his home in Edinburgh in 1799 at the age of 71 and is buried in Greyfriars Kirkyard.

In 2011 scientific equipment believed to belong to Black was discovered during an archaeological dig at the University of Edinburgh.^[7]

Antoine Lavoisier

From Wikipedia, the free encyclopedia

Antoine-Laurent de Lavoisier
Line engraving by Louis Jean Desire Delaistre, after a design by Julien Leopold Boilly
Born	26 August 1743 Paris, France
Died	8 May 1794 (aged 50) Paris, France
Fields	biologist, chemist
Known for	Combustion Identified Oxygen Identified Hydrogen Stoichiometry
Influences	Guillaume-François Rouelle, Étienne Condillac
Signature

Antoine-Laurent de Lavoisier (also Antoine Lavoisier after the French Revolution; 26 August 1743 – 8 May 1794; French pronunciation: ​[ɑ̃twan lɔʁɑ̃ də lavwazje]) was a French nobleman and chemist central to the 18th-century Chemical Revolution and a large influence on both the histories of chemistry and biology.^[1] He is widely considered to be the "Father of Modern Chemistry."^[2]

It is generally accepted that Lavoisier's great accomplishments in chemistry largely stem from the fact that he changed the science from a qualitative to a quantitative one. Lavoisier is most noted for his discovery of the role oxygen plays in combustion. He recognized and named oxygen (1778) and hydrogen (1783) and opposed the phlogiston theory. Lavoisier helped construct the metric system, wrote the first extensive list of elements, and helped to reform chemical nomenclature. He predicted the existence of silicon (1787)^[3] and was also the first to establish that sulfur was an element (1777) rather than a compound.^[4] He discovered that, although matter may change its form or shape, its mass always remains the same.

Lavoisier was an administrator of the Ferme Générale and a powerful member of a number of other aristocratic councils. All of these political and economic activities enabled him to fund his scientific research. At the height of the French Revolution, he was accused by Jean-Paul Marat of selling adulterated tobacco and of other crimes, and was eventually guillotined a year after Marat's death.

Biography

Early life and education

Antoine-Laurent Lavoisier was born to a wealthy family in Paris on 26 August 1743. The son of an attorney at the Parlement of Paris, he inherited a large fortune at the age of five with the passing of his mother.^[5] Lavoisier began his schooling at the Collège des Quatre-Nations (known as the Collège Mazarin) in Paris in 1754 at the age of 11. In his last two years (1760–1761) at the college his scientific interests were aroused, and he studied chemistry, botany, astronomy, and mathematics. In the philosophy class he came under the tutelage of Abbé Nicolas Louis de Lacaille, a distinguished mathematician and observational astronomer who imbued the young Lavoisier with an interest in meteorological observation, an enthusiasm which never left him. Lavoisier entered the school of law, where he received a bachelor's degree in 1763 and a licentiate in 1764. Lavoisier received a law degree and was admitted to the bar, but never practiced as a lawyer. However, he continued his scientific education in his spare time.

Early scientific work

Lavoisier's education was filled with the ideals of the French Enlightenment of the time, and he was fascinated by Pierre Macquer's dictionary of chemistry. He attended lectures in the natural sciences. Lavoisier's devotion and passion for chemistry were largely influenced by Étienne Condillac, a prominent French scholar of the 18th century. His first chemical publication appeared in 1764. From 1763 to 1767, he studied geology under Jean-Étienne Guettard. In collaboration with Guettard, Lavoisier worked on a geological survey of Alsace-Lorraine in June 1767. In 1764 he read his first paper to the French Academy of Sciences, France's most elite scientific society, on the chemical and physical properties of gypsum (hydrated calcium sulfate), and in 1766 he was awarded a gold medal by the King for an essay on the problems of urban street lighting. In 1768 Lavoisier received a provisional appointment to the Academy of Sciences. In 1769, he worked on the first geological map of France.^[6]

Ferme générale and marriage

Portrait of Antoine-Laurent Lavoisier and his wife by Jacques-Louis David, ca. 1788

At age 26, around the time he was elected to the Academy of Sciences, Lavoisier bought a share in the Ferme générale, a tax farming financial company which advanced the estimated tax revenue to the royal government in return for the right to collect the taxes. Lavoisier attempted to introduce reforms in the French monetary and taxation system to help the peasants. While in government work, he helped develop the metric system to secure uniformity of weights and measures throughout France. Lavoisier consolidated his social and economic position when, in 1771 at age 28, he married Marie-Anne Pierrette Paulze, the 13-year-old daughter of a senior member of the Ferme générale.^[7]
She was to play an important part in Lavoisier's scientific career—notably, she translated English documents for him, including Richard Kirwan's Essay on Phlogiston and Joseph Priestley's research. In addition, she assisted him in the laboratory and created many sketches and carved engravings of the laboratory instruments used by Lavoisier and his colleagues for their scientific works.
Madame Lavoisier edited and published Antoine's memoirs (whether any English translations of those memoirs have survived is unknown as of today) and hosted parties at which eminent scientists discussed ideas and problems related to chemistry.^[8] For 3 years following his entry into the Ferme générale, Lavoisier's scientific activity diminished somewhat, for much of his time was taken up with official Ferme générale business. He did, however, present one important memoir to the Academy of
Sciences during this period, on the supposed conversion of water into earth by evaporation. By a very precise quantitative experiment Lavoisier showed that the "earthy" sediment produced after long-continued reflux heating of water in a glass vessel was not due to a conversion of the water into earth but rather to the gradual disintegration of the inside of the glass vessel produced by the boiling water.

Oxygen theory of combustion

Antoine Lavoisier's famous phlogiston experiment. Engraving by Mme Lavoisier in the 1780s taken from Traité élémentaire de chimie (Elementary treatise on chemistry)

During late 1772 Lavoisier turned his attention to the phenomenon of combustion, the topic on which he was to make his most significant contribution to science. He reported the results of his first experiments on combustion in a note to the Academy on 20 October, in which he reported that when phosphorus burned, it combined with a large quantity of air to produce acid spirit of phosphorus (phosphoric acid), and that the phosphorus increased in weight on burning. In a second sealed note deposited with the Academy a few weeks later (1 November) Lavoisier extended his observations and conclusions to the burning of sulfur and went on to add that "what is observed in the combustion of sulfur and phosphorus may well take place in the case of all substances that gain in weight by combustion and calcination: and I am persuaded that the increase in weight of metallic calces is due to the same cause."

Joseph Black's "fixed air"

During 1773 Lavoisier determined to review thoroughly the literature on air, particularly "fixed air," and to repeat many of the experiments of other workers in the field. He published an account of this review in 1774 in a book entitled Opuscules physiques et chimiques (Physical and Chemical Essays). In the course of this review he made his first full study of the work of Joseph Black, the Scottish chemist who had carried out a series of classic quantitative experiments on the mild and caustic alkalies. Black had shown that the difference between a mild alkali, for example, chalk (CaCO₃), and the caustic form, for example, quicklime (CaO), lay in the fact that the former contained "fixed air," not common air fixed in the chalk, but a distinct chemical species, carbon dioxide (CO₂), which was a constituent of the atmosphere. Lavoisier recognized that Black's fixed air was identical with the air evolved when metal calces were reduced with the charcoal and even suggested that the air which combined with metals on calcination and increased the weight might be Black's fixed air, that is, CO₂.

Joseph Priestley

Joseph Priestley, an English chemist known for isolating oxygen, which he termed "dephlogisticated air."

In the spring of 1774 Lavoisier carried out experiments on the calcination of tin and lead in sealed vessels which conclusively confirmed that the increase in weight of metals on calcination was due to combination with air. But the question remained about whether it was combination with common atmospheric air or with only a part of atmospheric air. In October the English chemist Joseph Priestley visited Paris, where he met Lavoisier and told him of the air which he had produced by heating the red calx of mercury with a burning glass and which had supported combustion with extreme vigor. Priestley at this time was unsure of the nature of this gas, but he felt that it was an especially pure form of common air. Lavoisier carried out his own researches on this peculiar substance. The result was his famous memoir On the Nature of the Principle Which Combines with Metals during Their Calcination and Increases Their Weight, read to the Academy on 26 April 1775 (commonly referred to as the Easter Memoir). In the original memoir Lavoisier showed that the mercury calx was a true metallic calx in that it could be reduced with charcoal, giving off Black's fixed air in the process.^[9] When reduced without charcoal, it gave off an air which supported respiration and combustion in an enhanced way. He concluded that this was just a pure form of common air, and that it was the air itself "undivided, without alteration, without decomposition" which combined with metals on calcination.

After returning from Paris, Priestley took up once again his investigation of the air from mercury calx. His results now showed that this air was not just an especially pure form of common air but was "five or six times better than common air, for the purpose of respiration, inflammation, and ... every other use of common air." He called the air dephlogisticated air, as he thought it was common air deprived of its phlogiston. Since it was therefore in a state to absorb a much greater quantity of phlogiston given off by burning bodies and respiring animals, the greatly enhanced combustion of substances and the greater ease of breathing in this air were explained.

Easter memoir

The "official" version of Lavoisier's Easter Memoir appeared in 1778. In the intervening period Lavoisier had ample time to repeat some of Priestley's latest experiments and perform some new ones of his own. In addition to studying Priestley's dephlogisticated air, he studied more thoroughly the residual air after metals had been calcined. He showed that this residual air supported neither combustion nor respiration and that approximately five volumes of this air added to one volume of the dephlogisticated air gave common atmospheric air. Common air was then a mixture of two distinct chemical species with quite different properties. Thus when the revised version of the Easter
Memoir was published in 1778, Lavoisier no longer stated that the principle which combined with metals on calcination was just common air but "nothing else than the healthiest and purest part of the air" or the "eminently respirable part of the air." In the following year Lavoisier coined the name oxygen for this constituent of the air, from the Greek words meaning "acid former."^[9] and "Considérations générales sur la nature des acides" ("General Considerations on the Nature of Acids," 1778),^[10] He was struck by the fact that the combustion products of such nonmetals as sulfur, phosphorus, charcoal, and nitrogen were acidic. He held that all acids contained oxygen and that oxygen was therefore the acidifying principle.

Dismantling phlogiston theory

Lavoisier's chemical research between 1772 and 1778 was largely concerned with developing his own new theory of combustion. In 1783 he read to the academy his famous paper entitled Réflexions sur le phlogistique (Reflections on Phlogiston), a full-scale attack on the current phlogiston theory of combustion. That year Lavoisier also began a series of experiments on the composition of water which were to prove an important capstone to his combustion theory and win many converts to it. Many investigators had been experimenting with the combination of Henry Cavendish's inflammable air, which Lavoisier termed hydrogen (Greek for "water-former"), with dephlogisticated air (oxygen) by electrically sparking mixtures of the gases. All of the researchers noted the production of water, but all interpreted the reaction in varying ways within the framework of the phlogiston theory. In cooperation with mathematician Pierre Simon de Laplace, Lavoisier synthesized water by burning jets of hydrogen and oxygen in a bell jar over mercury. The quantitative results were good enough to support the contention that water was not an element, as had been thought for over 2,000 years, but a compound of two gases, hydrogen and oxygen.

Gunpowder Commission

Lavoisier's researches on combustion were carried out in the midst of a very busy schedule of public and private duties, especially in connection with the Ferme générale. There were also innumerable reports for and committees of the Academy of Sciences to investigate specific problems on order of the royal government. Lavoisier, whose organizing skills were outstanding, frequently landed the task of writing up such official reports. In 1775 he was made one of four commissioners of gunpowder appointed to replace a private company, similar to the Ferme générale, which had proved unsatisfactory in supplying France with its munitions requirements. As a result of his efforts, both the quantity and quality of French gunpowder greatly improved, and it became a source of revenue for the government. His appointment to the Gunpowder Commission brought one great benefit to Lavoisier's scientific career as well. As a commissioner, he enjoyed both a house and a laboratory in the Royal Arsenal. Here he lived and worked between 1775 and 1792.

Pioneer of stoichiometry

Lavoisier's researches included some of the first truly quantitative chemical experiments. He carefully weighed the reactants and products of a chemical reaction in a sealed glass vessel, which was a crucial step in the advancement of chemistry.^[11] In 1774, he showed that, although matter can change its state in a chemical reaction, the total mass of matter is the same at the end as at the beginning of every chemical change. Thus, for instance, if a piece of wood is burned to ashes, the total mass remains unchanged. Lavoisier's experiments supported the law of conservation of mass. In France it is taught as Lavoisier's Law and is paraphrased from a statement in his "Traité Élémentaire de Chimie" to "Rien ne se perd, rien ne se crée, tout se transforme." ("Nothing is lost, nothing is created, everything is transformed."). Mikhail Lomonosov (1711–1765) had previously expressed similar ideas in 1748 and proved them in experiments; others whose ideas pre-date the work of Lavoisier include Jean Rey (1583–1645), Joseph Black (1728–1799), and Henry Cavendish (1731–1810). (See An Historical Note on the Conservation of Mass)

Chemical nomenclature

Lavoisier's Laboratory, Musée des Arts et Métiers, Paris.

Lavoisier, together with L. B. Guyton de Morveau, Claude-Louis Berthollet, and Antoine François de Fourcroy, submitted a new program for the reforms of chemical nomenclature to the Academy in 1787, for there was virtually no rational system of chemical nomenclature at this time. The new system was tied inextricably to Lavoisier's new oxygen theory of chemistry. The Classical elements of earth, air, fire, and water were discarded, and instead some 55 substances which could not be decomposed into simpler substances by any known chemical means were provisionally listed as elements. The elements included light; caloric (matter of heat); the principles of oxygen, hydrogen, and azote (nitrogen); carbon; sulfur; phosphorus; the yet unknown "radicals" of muriatic acid (hydrochloric acid), boracic acid, and "fluoric" acid; 17 metals; 5 earths (mainly oxides of yet unknown metals such as magnesia, barite, and strontia); three alkalies (potash, soda, and ammonia); and the "radicals" of 19 organic acids. The acids, regarded in the new system as compounds of various elements with oxygen, were given names which indicated the element involved together with the degree of oxygenation of that element, for example sulfuric and sulfurous acids, phosphoric and phosphorus acids, nitric and nitrous acids, the "ic" termination indicating acids with a higher proportion of oxygen than those with the "ous" ending. Similarly, salts of the "ic" acids were given the terminal letters "ate," as in copper sulfate, whereas the salts of the"ous" acids terminated with the suffix "ite," as in copper sulfite. The total effect of the new nomenclature can be gauged by comparing the new name "copper sulfate" with the old term "vitriol of Venus." Lavoisier described this system of nomenclature in Méthode de nomenclature chimique (Method of Chemical Nomenclature, 1787).

Elementary Treatise of Chemistry

Lavoisier employed the new nomenclature in his Traité Élémentaire de Chimie (Elementary Treatise on Chemistry), published in 1789. This work represents the synthesis of Lavoisier's contribution to chemistry and can be considered the first modern textbook on the subject. The core of the work was the oxygen theory, and the work became a most effective vehicle for the transmission of the new doctrines. It presented a unified view of new theories of chemistry, contained a clear statement of the law of conservation of mass, and denied the existence of phlogiston. This text clarified the concept of an element as a substance that could not be broken down by any known method of chemical analysis, and presented Lavoisier's theory of the formation of chemical compounds from elements. It remains a classic in the history of science. While many leading chemists of the time refused to accept Lavoisier's new ideas, demand for Traité élémentaire as a textbook in Edinburgh was sufficient to merit translation into English within about a year of its French publication.^[12] In any event, the Traité élémentaire was sufficiently sound to convince the next generation.

Lavoisier conducting an experiment on respiration in the 1770s

Physiological work

Constant-pressure calorimeter, engraving made by madame Lavoisier for thermochemistry experiments

The relationship between combustion and respiration had long been recognized from the essential role which air played in both processes. Lavoisier was almost obliged, therefore, to extend his new theory of combustion to include the area of respiration physiology. His first memoirs on this topic were read to the Academy of Sciences in 1777, but his most significant contribution to this field was made in the winter of 1782/1783 in association with Laplace. The result of this work was published in a famous memoir, "On Heat." Lavoisier and Laplace designed an ice calorimeter apparatus for measuring the amount of heat given off during combustion or respiration. The outer shell of the calorimeter was packed with snow, which melted to maintain a constant temperature of 0 °C around an inner shell filled with ice. By measuring the quantity of carbon dioxide and heat produced by confining a live guinea pig in this apparatus, and by comparing the amount of heat produced when sufficient carbon was burned in the ice calorimeter to produce the same amount of carbon dioxide as that which the guinea pig exhaled, they concluded that respiration was in fact a slow combustion process. Lavoisier stated, "la respiration est donc une combustion," that is, respiratory gas exchange is a combustion, like that of a candle burning.^[13]

This continuous slow combustion, which they supposed took place in the lungs, enabled the living animal to maintain its body temperature above that of its surroundings, thus accounting for the puzzling phenomenon of animal heat. Lavoisier continued these respiration experiments in 1789–1790 in cooperation with Armand Seguin. They designed an ambitious set of experiments to study the whole process of body metabolism and respiration using Seguin as a human guinea pig in the experiments. Their work was only partially completed and published because of the disruption of the Revolution; but Lavoisier's pioneering work in this field served to inspire similar research on physiological processes for generations to come.

Final days and execution

As the French Revolution gained momentum from 1789 on, Lavoisier's world inexorably collapsed around him. Attacks mounted on the deeply unpopular Ferme Générale, and it was eventually suppressed in 1791. In 1792 Lavoisier was forced to resign from his post on the Gunpowder Commission and to move from his house and laboratory at the Royal Arsenal. On 8 August 1793, all the learned societies, including the Academy of Sciences, were suppressed.

It is difficult to assess Lavoisier's own attitude to the political turmoil. Like so many intellectual liberals, he felt that the Ancien Régime could be reformed from the inside if only reason and moderation prevailed. Characteristically, one of his last major works was a proposal to the National Convention for the reform of French education. He tried to remain aloof from the political cockpit, no doubt fearful and uncomprehending of the violence he saw therein. However, on 24 November 1793, the arrest of all the former tax gatherers was ordered. He was branded a traitor by the Convention under Maximilien de Robespierre during the Reign of Terror, in 1794. He had also intervened on behalf of a number of foreign-born scientists including mathematician Joseph Louis Lagrange, resulting in the granting to them of exceptions from a mandate stripping all foreigners of possessions and freedom.^[14] Lavoisier was tried, convicted, and guillotined on 8 May 1794 in Paris, at the age of 50, along with his 27 co-defendants.^[15]

According to a (probably apocryphal) story, the appeal to spare his life so that he could continue his experiments was cut short by the judge: "La République n'a pas besoin de savants ni de chimistes ; le cours de la justice ne peut être suspendu." ("The Republic needs neither scientists nor chemists; the course of justice cannot be delayed.")^[16] Lavoisier was convicted with summary justice of having plundered the people and the treasury of France, of having adulterated the nation's tobacco with water, and of having supplied the enemies of France with huge sums of money from the national treasury.

Lavoisier's importance to science was expressed by Joseph Louis Lagrange who lamented the beheading by saying: "Il ne leur a fallu qu’un moment pour faire tomber cette tête, et cent années peut-être ne suffiront pas pour en reproduire une semblable." ("It took them only an instant to cut off this head, and one hundred years might not suffice to reproduce its like.")^[17][18]

Post-mortem

Statue of Lavoisier, at Hôtel de Ville, Paris

A year and a half after his death, Lavoisier was exonerated by the French government. When his private belongings were delivered to his widow, a brief note was included, reading "To the widow of Lavoisier, who was falsely convicted".^{[citation needed]}

About a century after his death, a statue of Lavoisier was erected in Paris. It was later discovered that the sculptor had not actually copied Lavoisier's head for the statue, but used a spare head of the Marquis de Condorcet, the Secretary of the Academy of Sciences during Lavoisier's last years.^{[citation needed]} Lack of money prevented alterations from being made. The statue was melted down during the Second World War and has not since been replaced. However, one of the main "lycées" (high schools) in Paris and a street in the 8th arrondissement are named after Lavoisier, and statues of him are found on the Hôtel de Ville and on the façade of the Cour Napoléon of the Louvre. His name is one of the 72 names of eminent French scientists, engineers and mathematicians inscribed on the Eiffel Tower as well as on buildings around Killian Court at MIT in Cambridge, MA US.

Lavoisier is listed among eminent Roman Catholic scientists, and as such he defended his faith against those who attempted to use science to attack it. Louis Edouard Grimaux, author of the standard French biography of Lavoisier, and the first biographer to obtain access to Lavoisier's papers, writes the following:

Raised in a pious family which had given many priests to the Church, he had held to his beliefs. To Edward King, an English author who had sent him a controversial work, he wrote, "You have done a noble thing in upholding revelation and the authenticity of the Holy Scripture, and it is remarkable that you are using for the defense precisely the same weapons which were once used for the attack".^[19]

Legacy

The work of Lavoisier was translated in Japan in the 1840s, through the process of Rangaku. Page from Udagawa Yōan's 1840 Seimi Kaisō

Lavoisier's fundamental contributions to chemistry were a result of a conscious effort to fit all experiments into the framework of a single theory. He established the consistent use of the chemical balance, used oxygen to overthrow the phlogiston theory, and developed a new system of chemical nomenclature which held that oxygen was an essential constituent of all acids (which later turned out to be erroneous). Lavoisier also did early research in physical chemistry and thermodynamics in joint experiments with Laplace. They used a calorimeter to estimate the heat evolved per unit of carbon dioxide produced, eventually finding the same ratio for a flame and animals, indicating that animals produced energy by a type of combustion reaction.

Lavoisier also contributed to early ideas on composition and chemical changes by stating the radical theory, believing that radicals, which function as a single group in a chemical process, combine with oxygen in reactions. He also introduced the possibility of allotropy in chemical elements when he discovered that diamond is a crystalline form of carbon.

He was essentially a theorist, and his great merit lay in his capacity to take over experimental work that others had carried out—without always adequately recognizing their claims—and by a rigorous logical procedure, reinforced his own quantitative experiments, expounding the true explanation of the results.^{[citation needed]} He completed the work of Black, Priestley and Cavendish, and gave a correct explanation of their experiments.

Overall, his contributions are considered the most important in advancing chemistry to the level reached in physics and mathematics during the 18th century.^[20] Lavoisier's work was recognized as an International Historic Chemical Landmark by the American Chemical Society, Académie des sciences de L'institut de France and the Société Chimique de France in 1999.^[21]

Selected writings

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By Antoine Lavoisier
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• Opuscules physiques et chimiques (Paris: Chez Durand, Didot, Esprit, 1774). (Second edition, 1801)
• L'art de fabriquer le salin et la potasse, publié par ordre du Roi, par les régisseurs-généraux des Poudres & Salpêtres (Paris, 1779).
• Instruction sur les moyens de suppléer à la disette des fourrages, et d'augmenter la subsistence des bestiaux, Supplément à l'instruction sur les moyens de pourvoir à la disette des fourrages, publiée par ordre du Roi le 31 mai 1785 (Instruction on the means of compensating for the food shortage with fodder, and of increasing the subsistence of cattle, Supplement to the instruction on the means of providing for the food shortage with fodder, published by order of King on 31 May 1785).
• (with Guyton de Morveau, Claude-Louis Berthollet, Antoine Fourcroy) Méthode de nomenclature chimique (Paris: Chez Cuchet, 1787)
• (with Fourcroy, Morveau, Cadet, Baumé, d'Arcet, and Sage) Nomenclature chimique, ou synonymie ancienne et moderne, pour servir à l'intelligence des auteurs. (Paris: Chez Cuchet, 1789)
• Traité élémentaire de chimie, présenté dans un ordre nouveau et d'après les découvertes modernes (Paris: Chez Cuchet, 1789; Bruxelles: Cultures et Civilisations, 1965) (lit. Elementary Treatise on Chemistry, presented in a new order and alongside modern discoveries) also here
• (with Pierre-Simon Laplace) "Mémoire sur la chaleur," Mémoires de l'Académie des sciences (1780), pp. 355–408.
• Mémoire contenant les expériences faites sur la chaleur, pendant l'hiver de 1783 à 1784, par P.S. de Laplace & A. K. Lavoisier (1792)
• Mémoires de physique et de chimie (1805: posthumous)

In translation

• Essays Physical and Chemical (London: for Joseph Johnson, 1776; London: Frank Cass and Company Ltd., 1970) translation by Thomas Henry of Opuscules physiques et chimiques
• The Art of Manufacturing Alkaline Salts and Potashes, Published by Order of His Most Christian Majesty, and approved by the Royal Academy of Sciences (1784) trans. by Charles Williamos^[22] of L'art de fabriquer le salin et la potasse
• (with Pierre-Simon Laplace) Memoir on Heat:Read to the Royal Academy of Sciences, 28 June 1783, by Messrs. Lavoisier & De La Place of the same Academy. (New York: Neale Watson Academic Publications, 1982) trans. by Henry Guerlac of Mémoire sur la chaleur
• Essays, on the Effects Produced by Various Processes On Atmospheric Air; With A Particular View To An Investigation Of The Constitution Of Acids, trans. Thomas Henry (London: Warrington, 1783) collects these essays:

1. "Experiments on the Respiration of Animals, and on the Changes effected on the Air in passing through their Lungs." (Read to the Académie des Sciences, 3 May 1777)
2. "On the Combustion of Candles in Atmospheric Air and in Dephlogistated Air." (Communicated to the Académie des Sciences, 1777)
3. "On the Combustion of Kunckel's Phosphorus."
4. "On the Existence of Air in the Nitrous Acid, and on the Means of decomposing and recomposing that Acid."
5. "On the Solution of Mercury in Vitriolic Acid."
6. "Experiments on the Combustion of Alum with Phlogisic Substances, and on the Changes effected on Air in which the Pyrophorus was burned."
7. "On the Vitriolisation of Martial Pyrites."
8. "General Considerations on the Nature of Acids, and on the Principles of which they are composed."
9. "On the Combination of the Matter of Fire with Evaporable Fluids; and on the Formation of Elastic Aëriform Fluids."

• Method of chymical nomenclature: proposed by Messrs. De Moreau, Lavoisier, Bertholet, and De Fourcroy (1788) Dictionary
• Elements of Chemistry, in a New Systematic Order, Containing All the Modern Discoveries (Edinburgh: William Creech, 1790; New York: Dover, 1965) translation by Robert Kerr of Traité élémentaire de chimie. ISBN 978-0486646244 (Dover).
  • 1799 edition
  • 1802 edition: volume 1, volume 2
  • Some illustrations from 1793 edition
  • Some more illustrations from Othmer Library of Chemical History
  • More illustrations (from Collected Works) at Othmer Library of Chemical History