proposed the phlogiston theory]] The phlogiston theory (from the Ancient Greek φλογιστόν phlogistón "burning up", from φλόξ phlóx "flame"), first stated in 1667 by Johann Joachim Becher, is an obsolete scientific theory that postulated the existence of a fire-like element called "phlogiston", which was contained within combustible bodies and released during combustion. The theory was an attempt to explain processes such as combustion and the rusting of metals, which are now collectively known as oxidation.

processes such as fire and rust]]

Theory

The theory holds that all combustible resources contain phlogiston, a substance without colour, odor, taste, or mass that is liberated in burning. Once burned, the "dephlogisticated" substance was held to be in its "true" form, the calx.

"Phlogisticated" substances are those that contain phlogiston and are "dephlogisticated" when burned; "in general, substances that burned in air were said to be rich in phlogiston; the fact that combustion soon ceased in an enclosed space was taken as clear-cut evidence that air had the capacity to absorb only a definite amount of phlogiston. When air had become completely phlogisticated it would no longer serve to support combustion of any material, nor would a metal heated in it yield a calx; nor could phlogisticated air support life, for the role of air in respiration was to remove the phlogiston from the body."

Thus, phlogiston was described in a way basically the opposite of the real role of oxygen in combustion.

Joseph Black's student Daniel Rutherford discovered nitrogen in 1772 and the pair used the theory to explain his results. The residue of air left after burning, in fact a mixture of nitrogen and carbon dioxide, was sometimes referred to as "phlogisticated air", having taken up all of the phlogiston. Conversely, when oxygen was first discovered it was thought to be "dephlogisticated air", capable of combining with more phlogiston and thus supporting combustion for longer than ordinary air.

History

In 1667, Johann Joachim Becher published his Physical Education, which was the first mention of what would become the phlogiston theory. Traditionally, alchemists considered that there were four classical elements: fire, water, air, and earth. In his book, Becher eliminated fire and air from the classical element model and replaced them with three forms of earth: terra lapidea, terra fluida, and terra pinguis. Terra pinguis was the element which imparted oily, sulphurous, or combustible properties. Becher believed that terra pinguis was a key feature of combustion and was released when combustible substances were burned. In 1703 Georg Ernst Stahl, professor of medicine and chemistry at Halle, proposed a variant of the theory in which he renamed Becher's terra pinguis to phlogiston, and it was in this form that the theory probably had its greatest influence.

Challenge and demise

Eventually, quantitative experiments revealed problems, including the fact that some metals, such as magnesium, gained weight when they burned, even though they were supposed to have lost phlogiston. Mikhail Lomonosov attempted to repeat Robert Boyle's celebrated experiment in 1753 and concluded that the phlogiston theory was false. He wrote in his diary:

"Today I made an experiment in hermetic glass vessels in order to determine whether the mass of metals increases from the action of pure heat. The experiment demonstrated that the famous Robert Boyle was deluded, for without access of air from outside, the mass of the burnt metal remains the same."

Some phlogiston proponents explained this by concluding that phlogiston had negative weight; others, such as Louis-Bernard Guyton de Morveau, gave the more conventional argument that it was lighter than air. However, a more detailed analysis based on the Archimedean principle and the densities of magnesium and its combustion product shows that just being lighter than air cannot account for the increase in mass.

During the eighteenth century, as it became clear that metals gained weight when they were oxidized, phlogiston was increasingly regarded as a principle rather than a material substance. By the end of the eighteenth century, for the few chemists who still used the term phlogiston, the concept was linked to hydrogen. Joseph Priestley, for example, in referring to the reaction of steam on iron, whilst fully acknowledging that the iron gains weight as it binds with oxygen to form a calx, iron oxide, iron also loses “the basis of inflammable air (hydrogen), and this is the substance or principle, to which we give the name phlogiston.” Following Lavoisier’s description of oxygen as the oxidizing principle (hence the name oxygen: oxus = sharp, acid; geneo = I beget), Priestley described phlogiston as the alkaline principle.

Phlogiston remained the dominant theory until Antoine-Laurent Lavoisier showed that combustion requires a gas that has weight (oxygen) and could be measured by means of weighing closed vessels. The use of closed vessels also negated the buoyancy which had disguised the weight of the gases of combustion. These observations solved the weight paradox and set the stage for the new caloric theory of combustion.

Enduring aspects

Phlogiston theory permitted chemists to bring clarification of apparently different phenomena into a coherent structure: combustion, metabolism, and configuration of rust. The recognition of the relation between combustion and metabolism was a forerunner of the recognition that the metabolism of living organisms and combustion can be understood in terms of fundamentally related chemical processes.

Notes

Category:Obsolete scientific theories Category:History of chemistry

Name	Antoine Lavoisier
Caption	Line engraving by Louis Jean Desire Delaistre, after a design by Julien Leopold Boilly
Birth date	August 26, 1743
Birth place	Paris, France
Death date	May 08, 1794
Death place	Paris, France
Occupation	Chemist
Influences	Guillaume-François Rouelle
Influenced	Asfandyar Quereshi
Fields	biologist, chemist

, Paris.]] Antoine-Laurent de Lavoisier (also Antoine Lavoisier after the French Revolution); (26 August 1743 – 8 May 1794); (), the "father of modern chemistry", was a French nobleman prominent in the histories of chemistry and biology. He found and termed both oxygen (1778) and hydrogen (1783), helped construct the metric system, put together the first extensive list of elements, and helped to reform chemical nomenclature. He was also the first to establish that sulfur was an element (1777) rather than a compound. He discovered that, although matter may change its form or shape, its mass always remains the same.

He 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 watered-down tobacco, and of other crimes, and was guillotined.

Early life

by Jacques-Louis David, ca. 1788]] Born to a wealthy family in Paris, Antoine Laurent Lavoisier inherited a large fortune at the age of five with the passing of his mother. He attended the Collège Mazarin in 1754 to 1761, studying chemistry, botany, astronomy, and mathematics. His 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 was largely influenced by Étienne Condillac, a prominent French scholar of the 18th century. His first chemical publication appeared in 1764. In collaboration with Jean-Étienne Guettard, Lavoisier worked on a geological survey of Alsace-Lorraine in June 1767. At the age of 25, he was elected a member of the French Academy of Sciences, France's most elite scientific society, for an essay on street lighting, and in recognition for his earlier research. In 1769, he worked on the first geological map of France.

In 1771, at the age of 28, Lavoisier married 13-year-old Marie-Anne Pierrette Paulze, the daughter of a co-owner of the Ferme générale. Over time, she proved to be a scientific colleague to her husband. She translated documents from English for him, including Richard Kirwan's Essay on Phlogiston and Joseph Priestley's research. She created many sketches and carved engravings of the laboratory instruments used by Lavoisier and his colleagues. She edited and published Lavoisier’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.

Contributions to chemistry

Research on gases, water, and combustion

in the 1780s taken from Traité élémentaire de chimie (Elementary treatise on chemistry)]]

. Page from Udagawa Yōan's 1840 Seimi Kaisō]]

Lavoisier demonstrated the role of oxygen in the rusting of metal, as well as oxygen's role in animal and plant respiration. Working with Pierre-Simon Laplace, Lavoisier conducted experiments that showed that respiration was essentially a slow combustion of organic material using inhaled oxygen. Lavoisier's explanation of combustion disproved the phlogiston theory, which postulated that materials released a substance called phlogiston when they burned.

Lavoisier discovered that Henry Cavendish's "inflammable air", which Lavoisier had termed hydrogen (Greek for "water-former"), combined with oxygen to produce a dew which, as Joseph Priestley had reported, appeared to be water. In "Mémoire sur la combustion en général" ("On Combustion in General," 1777) and "Considérations générales sur la nature des acides" ("General Considerations on the Nature of Acids," 1778), he demonstrated that the "air" responsible for combustion was also the source of acidity. In 1779, he named this part of the air "oxygen" (Greek for "becoming sharp" because he claimed that the sharp taste of acids came from oxygen), and the other "azote" (Greek for "no life"). In "Réflexions sur le phlogistique" ("Reflections on Phlogiston," 1783), Lavoisier showed the phlogiston theory to be inconsistent. But Priestley refused to believe Lavoisier's results even on his death bed in Pennsylvania.

Pioneer of stoichiometry

Lavoisier's researches included some of the first truly quantitative chemical experiments. He carefully weighed the reactants and products in a chemical reaction, which was a crucial step in the advancement of chemistry. 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 water is heated to steam, if salt is dissolved in water or if a piece of wood is burned to ashes, the total mass remains unchanged. His experiments supported the law of conservation of mass, which Lavoisier was the first to state, In any event, the Traité élémentaire was sufficiently sound to convince the next generation.

materials using lenses, an experiment conducted by Lavoisier in the 1770s]]

Legacy

calorimeter, engraving made by madame Lavoisier for thermochemistry experiments]] 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.

However, much to his professional detriment, Lavoisier discovered no new substances, devised no really novel apparatus, and worked out no improved methods of preparation. He was essentially a theorist, and his great merit lay in the capacity of taking over experimental work that others had carried out—without always adequately recognizing their claims—and by a rigorous logical procedure, reinforced by his own quantitative experiments, of expounding the true explanation of the results. 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.

Contributions to biology

Lavoisier used a calorimeter to measure heat production as a result of respiration in a guinea pig. The outer shell of the calorimeter was packed with snow, which melted to maintain a constant temperature of around an inner shell filled with ice. The guinea pig in the center of the chamber produced heat which melted the ice. The water that flowed out of the calorimeter was collected and weighed. Lavoisier used this measurement to estimate the heat produced by the guinea pig's metabolism. Lavoisier concluded, "la respiration est donc une combustion," That is, respiratory gas exchange is a combustion, like that of a candle burning.

Law and politics

Lavoisier received a law degree and was admitted to the bar, but never practiced as a lawyer. He did become interested in French politics, and at the age of 26 he obtained a position as a tax collector in the Ferme Générale, a tax farming company, where he 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.

Final days, execution, and aftermath

He was a powerful figure in the deeply unpopular Ferme Générale, 28 feudal tax collectors who were known to profit immensely by exploiting their position. Lavoisier was branded a traitor by the Assembly under 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, granting them exception to a mandate stripping all foreigners of possessions and freedom. Lavoisier was tried, convicted, and guillotined on 8 May in Paris, at the age of 50.

Lavoisier was actually one of the few liberals in his position. One of his actions that may have sealed his fate (although all tax collectors were executed during the revolution) was a clash a few years earlier with the young Jean-Paul Marat whom he dismissed curtly after being presented with a preposterous "scientific invention" (an object which showed a spectrum of light that was as yet unseen — but did not measure anything). Marat subsequently became a leading agitator for the extension of the revolutions gains to the 'sans-cullottes' and a Jacobin.

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".)

Lavoisier's importance to science was expressed by Lagrange who lamented the beheading by saying: "Cela leur a pris seulement un instant pour lui couper la tête, mais la France pourrait ne pas en produire une autre pareille en un siècle." ("It took them only an instant to cut off his head, but France may not produce another such head in a century.")

One and a half years following 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."

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. Lack of money prevented alterations 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 (photograph, left) and on the façade of the Cour Napoléon of the Louvre.

Selected writings

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 May 31, 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 of L'art de fabriquer le salin et la potasse

(with Pierre-Simon Laplace) Memoir on Heat:Read to the Royal Academy of Sciences, June 28, 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:

# "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) # "On the Combustion of Candles in Atmospheric Air and in Dephlogistated Air." (Communicated to the Académie des Sciences, 1777) # "On the Combustion of Kunckel's Phosphorus." # "On the Existence of Air in the Nitrous Acid, and on the Means of decomposing and recomposing that Acid." # "On the Solution of Mercury in Vitriolic Acid." # "Experiments on the Combustion of Alum with Phlogisic Substances, and on the Changes effected on Air in which the Pyrophorus was burned." # "On the Vitriolisation of Martial Pyrites." # "General Considerations on the Nature of Acids, and on the Principles of which they are composed." # "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

*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

References

;Attribution

Further reading

, ca 1853, among culture heroes in the Louvre's ''Cour Napoléon]]

Catalogue of Printed Works by and Memorabilia of Antoine Laurent Lavoisier, 1743-1794... Exhibited at the Grolier Club (New York, 1952).

Duveen, D. I. and H. S. Klickstein, A Bibliography of the Works of Antoine Laurent Lavoisier, 1743-1794 (London, 1954)

External links

Panopticon Lavoisier a virtual museum of Antoine Lavoisier

Antoine Lavoisier Chemical Achievers profile

Antoine Laurent Lavoisier

About his work

Location of Lavoisier's laboratory in Paris

Radio 4 program on the discovery of oxygen by the BBC

Who was the first to classify materials as "compounds"? - Fred Senese

Cornell University's Lavoisier collection

His writings

Bibliography at Panopticon Lavoisier

Les Œuvres de Lavoisier (The Complete Works of Lavoisier) edited by Pietro Corsi (Oxford University) and Patrice Bret (CNRS) Oeuvres de Lavoisier (Works of Lavoisier) at Gallica BnF in six volumes.

Works of Lavoisier at Internet Archive

WorldCat author page

Elements of Chemistry - Google books version of the 1965 Dover reprint (limited preview)

Category:1743 births Category:Burials at the Picpus Cemetery, Paris Category:1794 deaths Category:Discoverers of chemical elements Category:Executed French people Category:Ferme générale Category:French biologists Category:French chemists Category:French Roman Catholics Category:Gentleman scientists Category:Members of the French Academy of Sciences Category:People executed by decapitation Category:People executed by guillotine during the French Revolution Category:People from Paris Category:University of Paris alumni Category:Fellows of the Royal Society