Nickel

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From Wikipedia, the free encyclopedia

Nickel,  ₂₈Ni

General properties
Name, symbol	nickel, Ni
Pronunciation	/ˈnɪkəl/ NIK-əl
Appearance	lustrous, metallic, and silver with a gold tinge
Nickel in the periodic table
– ↑ Ni ↓ Pd cobalt ← nickel → copper
Atomic number	28
Standard atomic weight (±)	58.6934(4)[1]
Element category	transition metal
Group, block	group 10, d-block
Period	period 4
Electron configuration	[Ar] 3d8 4s2 or [Ar] 3d9 4s1
per shell	2, 8, 16, 2 or 2, 8, 17, 1
Physical properties
Phase	solid
Melting point	1728 K ​(1455 °C, ​2651 °F)
Boiling point	3003 K ​(2730 °C, ​4946 °F)
Density near r.t.	8.908 g·cm−3
when liquid, at m.p.	7.81 g·cm−3
Heat of fusion	17.48 kJ·mol−1
Heat of vaporization	379 kJ·mol−1
Molar heat capacity	26.07 J·mol−1·K−1
vapor pressure P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 1783 1950 2154 2410 2741 3184
Atomic properties
Oxidation states	4,[2] 3, 2, 1,[3] −1 ​(a mildly basic oxide)
Electronegativity	Pauling scale: 1.91
Ionization energies	1st: 737.1 kJ·mol−1 2nd: 1753.0 kJ·mol−1 3rd: 3395 kJ·mol−1 (more)
Atomic radius	empirical: 124 pm
Covalent radius	124±4 pm
Van der Waals radius	163 pm
Miscellanea
Crystal structure	​face-centered cubic (fcc)
Speed of sound thin rod	4900 m·s−1 (at r.t.)
Thermal expansion	13.4 µm·m−1·K−1 (at 25 °C)
Thermal conductivity	90.9 W·m−1·K−1
Electrical resistivity	69.3 nΩ·m (at 20 °C)
Magnetic ordering	ferromagnetic
Young's modulus	200 GPa
Shear modulus	76 GPa
Bulk modulus	180 GPa
Poisson ratio	0.31
Mohs hardness	4.0
Vickers hardness	638 MPa
Brinell hardness	667–1600 MPa
CAS Registry Number	7440-02-0
History
Discovery and first isolation	Axel Fredrik Cronstedt (1751)
Most stable isotopes
Main article: Isotopes of nickel
iso NA half-life DM DE (MeV) DP 58Ni 68.077% >7×1020 y (β+β+) 1.9258 58Fe 59Ni trace 7.6×104 y ε – 59Co 60Ni 26.223% 60Ni is stable with 32 neutrons 61Ni 1.14% 61Ni is stable with 33 neutrons 62Ni 3.634% 62Ni is stable with 34 neutrons 63Ni syn 100.1 y β− 0.0669 63Cu 64Ni 0.926% 64Ni is stable with 36 neutrons
Decay modes in parentheses are predicted, but have not yet been observed

Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile. Pure nickel shows a significant chemical activity that can be observed when nickel is powdered to maximize the exposed surface area on which reactions can occur, but larger pieces of the metal are slow to react with air at ambient conditions due to the formation of a protective oxide surface. Even then, nickel is reactive enough with oxygen that native nickel is rarely found on Earth's surface, being mostly confined to the interiors of larger nickel–iron meteorites that were protected from oxidation during their time in space. On Earth, such native nickel is found in combination with iron, a reflection of those elements' origin as major end products of supernova nucleosynthesis. An iron–nickel mixture is thought to compose Earth's inner core.^[4]

The use of nickel (as a natural meteoric nickel–iron alloy) has been traced as far back as 3500 BCE. Nickel was first isolated and classified as a chemical element in 1751 by Axel Fredrik Cronstedt, who initially mistook its ore for a copper mineral. The element's name comes from a mischievous sprite of German miner mythology, Nickel (similar to Old Nick), that personified the fact that copper-nickel ores resisted refinement into copper. An economically important source of nickel is the iron ore limonite, which often contains 1-2% nickel. Nickel's other important ore minerals include garnierite, and pentlandite. Major production sites include the Sudbury region in Canada (which is thought to be of meteoric origin), New Caledonia in the Pacific, and Norilsk in Russia.

Because of nickel's slow rate of oxidation at room temperature, it is considered corrosion-resistant. Historically, this has led to its use for plating metals such as iron and brass, coating chemistry equipment, and manufacturing certain alloys that retain a high silvery polish, such as German silver. About 6% of world nickel production is still used for corrosion-resistant pure-nickel plating. Nickel-plated items are noted for provoking nickel allergy. Nickel has been widely used in coins, though its rising price has led to some replacement with cheaper metals in recent years.

Nickel is one of four elements that are ferromagnetic around room temperature. Alnico permanent magnets based partly on nickel are of intermediate strength between iron-based permanent magnets and rare-earth magnets. The metal is chiefly valuable in the modern world for the alloys it forms; about 60% of world production is used in nickel-steels (particularly stainless steel). Other common alloys, as well as some new superalloys, make up most of the remainder of world nickel use, with chemical uses for nickel compounds consuming less than 3% of production.^[5] As a compound, nickel has a number of niche chemical manufacturing uses, such as a catalyst for hydrogenation. Enzymes of some microorganisms and plants contain nickel as an active site, which makes the metal an essential nutrient for them.

§Properties

§Atomic and physical properties

Molar volume vs. pressure at room temperature

Nickel is a silvery-white metal with a slight golden tinge that takes a high polish. It is one of only four elements that are magnetic at or near room temperature, the others being iron, cobalt and gadolinium. Its Curie temperature is 355 °C (671 °F), meaning that bulk nickel is non-magnetic above this temperature.^[6] The unit cell of nickel is a face centered cube with the lattice parameter of 0.352 nm, giving an atomic radius of 0.124 nm. This crystal structure is stable to pressures of at least 70 GPa. Nickel belongs to the transition metals and is hard and ductile.

§Electron configuration dispute

The nickel atom has two electron configurations, [Ar] 3d⁸ 4s² and [Ar] 3d⁹ 4s¹, which are very close in energy – the symbol [Ar] refers to the argon-like core structure. There is some disagreement as to which should be considered the lowest energy configuration.^[7] Chemistry textbooks quote the electron configuration of nickel as [Ar] 4s² 3d⁸,^[8] or equivalently as [Ar] 3d⁸ 4s².^[9] This configuration agrees with the Madelung energy ordering rule, which predicts that 4s is filled before 3d. It is supported by the experimental fact that the lowest energy state of the nickel atom is a 3d⁸ 4s² energy level, specifically the 3d⁸(³F) 4s^{2 3}F, J = 4 level.^[10]

However, each of these configurations in fact gives rise to a set of states of different energies.^[10] The two sets of energies overlap, and the average energy of states having configuration [Ar] 3d⁹ 4s¹ is in fact lower than the average energy of states having configuration [Ar] 3d⁸ 4s². For this reason, the research literature on atomic calculations quotes the ground state configuration of nickel as [Ar] 3d⁹ 4s¹.^[7]

§Isotopes

Naturally occurring nickel is composed of five stable isotopes; 58
Ni, 60Ni, 61Ni, 62Ni and 64Ni with 58Ni being the most abundant (68.077% natural abundance). 62Ni has the highest nuclear binding energy of any nuclide. Its binding energy is greater than both 56Fe, often incorrectly cited as the largest, and 58Fe.^[11] 18 radioisotopes have been characterised with the most stable being 59Ni with a half-life of 76,000 years, 63Ni with a half-life of 100.1 years, and 56Ni with a half-life of 6.077 days. All of the remaining radioactive isotopes have half-lives that are less than 60 hours and the majority of these have half-lives that are less than 30 seconds. This element also has one meta state.^[12]

Nickel-56 is produced by the silicon burning process and later set free in large quantities during type Ia supernovae. The shape of the light curve of these supernovae at intermediate to late-times corresponds to the decay via electron capture of nickel-56 to cobalt-56 and ultimately to iron-56.^[13] Nickel-59 is a long-lived cosmogenic radionuclide with a half-life of 76,000 years. 59Ni has found many applications in isotope geology. 59Ni has been used to date the terrestrial age of meteorites and to determine abundances of extraterrestrial dust in ice and sediment. Nickel-60 is the daughter product of the extinct radionuclide 60Fe, which decays with a half-life of 2.6 million years. Because 60Fe has such a long half-life, its persistence in materials in the solar system at high enough concentrations may have generated observable variations in the isotopic composition of 60Ni. Therefore, the abundance of 60Ni present in extraterrestrial material may provide insight into the origin of the solar system and its early history. Nickel-62 has the highest binding energy per nucleon of any isotope for any element (8.7946 MeV/nucleon).^[14] Isotopes heavier than 62Ni cannot be formed by nuclear fusion without losing energy. ⁴⁸Ni, discovered in 1999, is the most proton-rich heavy element isotope known. With 28 protons and 20 neutrons ⁴⁸Ni is "double magic" (like ²⁰⁸Pb) and therefore unusually stable.^[12][15]

The isotopes of nickel range in atomic weight from 48 u (48Ni) to 78 u (78Ni). Nickel-78's half-life was recently measured at 110 milliseconds, and is believed an important isotope in supernova nucleosynthesis of elements heavier than iron.^[16]

§Occurrence

Widmanstätten pattern showing the two forms of nickel-iron, Kamacite and Taenite, in an octahedrite meteorite

On Earth, nickel occurs most often in combination with sulfur and iron in pentlandite, with sulfur in millerite, with arsenic in the mineral nickeline, and with arsenic and sulfur in nickel galena.^[17] Nickel is commonly found in iron meteorites as the alloys kamacite and taenite.

The bulk of the nickel mined comes from two types of ore deposits. The first are laterites, where the principal ore minerals are nickeliferous limonite: (Fe, Ni)O(OH) and garnierite (a hydrous nickel silicate): (Ni, Mg)
3Si
2O
5(OH)
4. The second are magmatic sulfide deposits, where the principal ore mineral is pentlandite: (Ni, Fe)
9S
8.

Australia and New Caledonia have the biggest estimate reserves (45% all together).^[18]

In terms of World Resources, identified land-based resources averaging 1% nickel or greater contain at least 130 million tons of nickel (about the double of known reserves). About 60% is in laterites and 40% is in sulfide deposits.^[18]

Based on geophysical evidence, most of the nickel on Earth is postulated to be concentrated in the Earth's outer and inner cores. Kamacite and taenite are naturally occurring alloys of iron and nickel. For kamacite, the alloy is usually in the proportion of 90:10 to 95:5, although impurities (such as cobalt or carbon) may be present, while for taenite the nickel content is between 20% and 65%. Kamacite and taenite occur in nickel iron meteorites.^[19]

§Compounds

Tetracarbonyl nickel

The most common oxidation state of nickel is +2, but compounds of Ni⁰, Ni⁺, and Ni³⁺ are well known, as well as exotic oxidation states Ni²⁻, Ni¹⁻, and Ni⁴⁺.^[20]

§Nickel(0)

Tetracarbonylnickel (Ni(CO)
4), discovered by Ludwig Mond,^[21] is a volatile, highly toxic liquid at room temperature. On heating, the complex decomposes back to nickel and carbon monoxide:

Ni(CO)
4 Ni + 4 CO

This behavior is exploited in the Mond process for purifying nickel, as described above. The related nickel(0) complex bis(cyclooctadiene)nickel(0) is a useful catalyst in organonickel chemistry due to the easily displaced cod ligands.

§Nickel(I)

Nickel(I) complexes are uncommon, however one example is the tetrahedral complex NiBr(PPh₃)₃. Many nickel(I) complexes feature Ni-Ni bonding, such as the dark red diamagnetic K
4[Ni
2(CN)
6] prepared by reduction of K
2[Ni
2(CN)
6] with sodium amalgam. This compound is oxidised in water, liberating H
2.^[22]

It is thought that the nickel(I) oxidation state is important to nickel-containing enzymes, such as [NiFe]-hydrogenase, which catalyzes the reversible reduction of protons to H
2.^[23]

Structure of [Ni
2(CN)
6]4− ion^[22]

§Nickel(II)

Color of various Ni(II) complexes in aqueous solution. From left to right, [Ni(NH
3)
6]2+, [Ni(C₂H₄(NH₂)₂)]²⁺, [NiCl
4]2−, [Ni(H
2O)
6]2+

Crystals of hydrated nickel sulfate.

Nickel(II) forms compounds with all common anions, i.e. the sulfide, sulfate, carbonate, hydroxide, carboxylates, and halides. Nickel(II) sulfate is produced in large quantities by dissolving nickel metal or oxides in sulfuric acid. It exists as both a hexa- and heptahydrates.^[24] This compound is useful for electroplating nickel. Common salts of nickel, such as the chloride, nitrate, and sulfate, dissolve in water to give green solutions containing the metal aquo complex [Ni(H
2O)
6]2+.

The four halides form nickel compounds. The structures of these solids feature octahedral Ni centres. Nickel(II) chloride is most common, and its behavior is illustrative of the other halides. Nickel(II) chloride is produced by dissolving nickel or its oxide in hydrochloric acid. It is usually encountered as the green hexahydrate, the formula of which is usually written NiCl₂•6H₂O. When dissolved in water, this salt forms the metal aquo complex [Ni(H
2O)
6]2+. Dehydration of NiCl₂•6H₂O gives the yellow anhydrous NiCl
2.

Some tetracoordinate nickel(II) complexes, e.g. bis(triphenylphosphine)nickel chloride, exist both in tetrahedral and square planar geometries. The tetrahedral complexes are paramagnetic whereas the square planar complexes are diamagnetic. This equilibrium as well as the formation of octahedral complexes contrasts with the behavior of the divalent complexes of the heavier group 10 metals, palladium(II) and platinum(II), which tend to adopt only square-planar geometry.^[20]

Nickelocene is known; it has an electron count of 20, making it relatively unstable.

Nickel(III) antimonide

§Nickel(III) and (IV)

For simple compounds, nickel(III) and nickel(IV) only occurs with fluoride and oxides, with the exception of KNiIO
6, which can be considered as a formal salt of the [IO
6]5− ion.^[22] Ni(IV) is present in the mixed oxide BaNiO
3, while Ni(III) is present in nickel(III) oxide, which is used as the cathode in many rechargeable batteries, including nickel-cadmium, nickel-iron, nickel hydrogen, and nickel-metal hydride, and used by certain manufacturers in Li-ion batteries.^[25] Nickel(III) can be stabilized by σ-donor ligands such as thiols and phosphines.^[22]

§History

Because the ores of nickel are easily mistaken for ores of silver, understanding of this metal and its use dates to relatively recent times. However, the unintentional use of nickel is ancient, and can be traced back as far as 3500 BCE. Bronzes from what is now Syria have been found to contain up to 2% nickel.^[26] Further, there are Chinese manuscripts suggesting that "white copper" (cupronickel, known as baitong) was used there between 1700 and 1400 BCE. This Paktong white copper was exported to Britain as early as the 17th century, but the nickel content of this alloy was not discovered until 1822.^[27]

In medieval Germany, a red mineral was found in the Erzgebirge (Ore Mountains) that resembled copper ore. However, when miners were unable to extract any copper from it, they blamed a mischievous sprite of German mythology, Nickel (similar to Old Nick), for besetting the copper. They called this ore Kupfernickel from the German Kupfer for copper.^{[28][29][30][31]} This ore is now known to be nickeline or niccolite, a nickel arsenide. In 1751, Baron Axel Fredrik Cronstedt was trying to extract copper from kupfernickel—and instead produced a white metal that he named after the spirit that had given its name to the mineral, nickel.^[32] In modern German, Kupfernickel or Kupfer-Nickel designates the alloy cupronickel.


After its discovery, the only source for nickel was the rare Kupfernickel but, from 1824 on, nickel was obtained as a byproduct of cobalt blue production. The first large-scale producer of nickel was Norway, which exploited nickel-rich pyrrhotite from 1848 on. The introduction of nickel in steel production in 1889 increased the demand for nickel, and the nickel deposits of New Caledonia, which were discovered in 1865, provided most of the world's supply between 1875 and 1915. The discovery of the large deposits in the Sudbury Basin, Canada, in 1883, in Norilsk-Talnakh, Russia, in 1920, and in the Merensky Reef, South Africa, in 1924 made large-scale production of nickel possible.^[27]

Dutch coins made of pure nickel

Nickel has been a component of coins since the mid-19th century. However, in Birmingham there were already Dutch silver 18th century coins forged in nickel around 1833 (meant for trading in Malaya).^[33] In the United States, the term "nickel" or "nick" originally applied to the copper-nickel Flying Eagle cent, which replaced copper with 12% nickel 1857–58, then the Indian Head cent of the same alloy from 1859–1864. Still later, in 1865, the term designated the three-cent nickel, with nickel increased to 25%. In 1866, the five-cent shield nickel (25% nickel, 75% copper) appropriated the designation. Along with the alloy proportion, this term has been used to the present in the United States. Coins of nearly pure nickel were first used in 1881 in Switzerland, and more notably 99.9% nickel five-cent coins were struck in Canada (the world's largest nickel producer at the time) during non-war years from 1922–1981, and their metal content made these coins magnetic.^[34] During the wartime period 1942–45, most or all nickel was removed from Canadian and U.S. coins, due to nickel's war-critical use in armor.^[29][35] Canada used 99.9% nickel from 1968 in its higher-value coins until 2000. In the 21st century, the high price of nickel has led to some replacement of the metal in coins around the world. Coins still made with nickel alloys include one- and two- Euro coins, 5¢, 10¢, 25¢ and 50¢ U.S. coins and 20p, 50p, £1 and £2 UK coins. The replacement of nickel-alloy 5p and 10p UK coins with nickel-plated steel models, begun in 2012, has caused dermatological controversy.^[36]

§World production

Time trend of nickel production ^[37]

The Philippines, Indonesia, Russia, Canada and Australia are the world's largest producers of nickel, as reported by the US Geological Survey.^[18] The largest deposits of nickel in non-Russian Europe are located in Finland and Greece. Identified land-based resources averaging 1% nickel or greater contain at least 130 million tons of nickel. About 60% is in laterites and 40% is in sulfide deposits. In addition, extensive deep-sea resources of nickel are in manganese crusts and nodules covering large areas of the ocean floor, particularly in the Pacific Ocean.^[38]

The one locality in the United States where nickel was commercially mined is Riddle, Oregon, where several square miles of nickel-bearing garnierite surface deposits are located. The mine closed in 1987.^[39][40] The Eagle mine project is a new nickel mine in Michigan's upper peninsula. Completed in 2013, it is expected to begin operations in the fourth quarter of 2014.^[41]

Mine production and reserves[38]	2012 (metric tons)	2011 (metric tons)	Reserves (metric tons)
Australia	230,000	215,000	20,000,000
Botswana	26,000	26,000	490,000
Brazil	140,000	209,000	7,500,000
Canada	220,000	220,000	3,300,000
China	91,000	89,800	3,000,000
Colombia	80,000	76,000	1,100,000
Cuba	72,000	71,000	5,500,000
Dominican Republic	24,000	21,700	970,000
Indonesia	320,000	290,000	3,900,000
Madagascar	22,000	5,900	1,600,000
New Caledonia	140,000	131,000	12,000,000
Philippines	330,000	270,000	1,100,000
Russia	270,000	267,000	6,100,000
South Africa	42,000	44,000	3,700,000
Other countries	120,000	103,000	4,600,000
World total (metric tons, rounded)	2,100,000	1,940,000	75,000,000

§Extraction and purification

Nickel is recovered through extractive metallurgy: it is extracted from its ores by conventional roasting and reduction processes that yield a metal of greater than 75% purity. In many stainless steel applications, 75% pure nickel can be used without further purification, depending on the composition of the impurities.

Most sulfide ores have traditionally been processed using pyrometallurgical techniques to produce a matte for further refining. Recent advances in hydrometallurgical techniques have resulted in significant nickel purification using these processes. Most sulfide deposits have traditionally been processed by concentration through a froth flotation process followed by pyrometallurgical extraction. In hydrometallurgical processes, nickel sulfide ores undergo flotation (differential flotation if Ni/Fe ratio is too low) and then smelted. After producing the nickel matte, further processing is done via the Sherritt-Gordon process. First, copper is removed by adding hydrogen sulfide, leaving a concentrate of only cobalt and nickel. Then, solvent extraction is used to separate the cobalt and nickel, with the final nickel concentration greater than 99%.

Electrolytically refined nickel nodule, with green, crystallized nickel-electrolyte salts visible in the pores.

§Electrorefining

A second common form of further refining involves the leaching of the metal matte into a nickel salt solution, followed by the electro-winning of the nickel from solution by plating it onto a cathode as electrolytic nickel.

§Mond process

Highly purified nickel spheres made by the Mond process.

Purification of nickel oxides to obtain the purest metal is performed via the Mond process, which increases the nickel concentrate to greater than 99.99% purity.^[42] This process was patented by Ludwig Mond and has been in industrial use since before the beginning of the 20th century. In the process, nickel is reacted with carbon monoxide at around 40–80 °C to form nickel carbonyl in the presence of a sulfur catalyst. Iron gives iron pentacarbonyl, too, but this reaction is slow. If necessary, the nickel may be separated by distillation. Dicobalt octacarbonyl is also formed in nickel distillation as a by-product, but it decomposes to tetracobalt dodecacarbonyl at the reaction temperature to give a non-volatile solid.^[5]

Nickel is re-obtained from the nickel carbonyl by one of two processes. It may be passed through a large chamber at high temperatures in which tens of thousands of nickel spheres, called pellets, are constantly stirred. It then decomposes, depositing pure nickel onto the nickel spheres. Alternatively, the nickel carbonyl may be decomposed in a smaller chamber at 230 °C to create a fine nickel powder. The resultant carbon monoxide is re-circulated and reused through the process. The highly pure nickel produced by this process is known as "carbonyl nickel".^[43]

§Metal value

The market price of nickel surged throughout 2006 and the early months of 2007; as of April 5, 2007, the metal was trading at US$52,300/tonne or $1.47/oz.^[44] The price subsequently fell dramatically from these peaks, and as of September 19, 2013 the metal was trading at $13,778/tonne, or $0.39/oz.^[45][46]

The US nickel coin contains 0.04 ounces (1.1 g) of nickel, which at the April 2007 price was worth 6.5 cents, along with 3.75 grams of copper worth about 3 cents, making the metal value over 9 cents. Since the face value of a nickel is 5 cents, this made it an attractive target for melting by people wanting to sell the metals at a profit. However, the United States Mint, in anticipation of this practice, implemented new interim rules on December 14, 2006, subject to public comment for 30 days, which criminalized the melting and export of cents and nickels.^[47] Violators can be punished with a fine of up to $10,000 and/or imprisoned for a maximum of five years.

As of September 19, 2013, the melt value of a U.S. nickel (copper and nickel included) is $0.0450258, which is 90% of its face value.^[48]

§Applications

Nickel superalloy jet engine (RB199) turbine blade

The fraction of global nickel production presently used for various applications is as follows: 46% for making nickel steels; 34% in nonferrous alloys and superalloys; 14% electroplating, and 6% into other uses.^[18][49]

Nickel is used in many specific and recognizable industrial and consumer products, including stainless steel, alnico magnets, coinage, rechargeable batteries, electric guitar strings, microphone capsules, and special alloys. It is also used for plating and as a green tint in glass. Nickel is preeminently an alloy metal, and its chief use is in the nickel steels and nickel cast irons, of which there are many varieties. It is also widely used in many other alloys, such as nickel brasses and bronzes, and alloys with copper, chromium, aluminium, lead, cobalt, silver, and gold (Inconel, Incoloy, Monel, Nimonic).^[50]

A "horseshoe magnet" made of alnico nickel alloy.

Because of its resistance to corrosion, nickel has been occasionally used historically as a substitute for decorative silver. Nickel was also occasionally used in some countries after 1859 as a cheap coinage metal (see above) but in the later years of the 20th century was largely replaced by cheaper stainless steel (i.e., iron) alloys, except notably in the United States and Canada.

Nickel is an excellent alloying agent for certain other precious metals, and so used in the so-called fire assay, as a collector of platinum group elements (PGE). As such, nickel is capable of full collection of all 6 PGE elements from ores, in addition to partial collection of gold. High-throughput nickel mines may also engage in PGE recovery (primarily platinum and palladium); examples are Norilsk in Russia and the Sudbury Basin in Canada.

Nickel foam or nickel mesh is used in gas diffusion electrodes for alkaline fuel cells.^[51][52]
Nickel and its alloys are frequently used as catalysts for hydrogenation reactions. Raney nickel, a finely divided nickel-aluminium alloy, is one common form, however related catalysts are also often used, including related 'Raney-type' catalysts.

Nickel is a naturally magnetostrictive material, meaning that, in the presence of a magnetic field, the material undergoes a small change in length.^[53][54] In the case of nickel, this change in length is negative (contraction of the material), which is known as negative magnetostriction and is on the order of 50 ppm.

Nickel is used as a binder in the cemented tungsten carbide or hardmetal industry and used in proportions of six to 12% by weight. Nickel can make the tungsten carbide magnetic and adds corrosion-resistant properties to the cemented tungsten carbide parts, although the hardness is lower than those of parts made with cobalt binder.^[55]

§Biological role

Although not recognized until the 1970s, nickel plays important roles in the biology of microorganisms and plants.^[56][57] The plant enzyme urease (an enzyme that assists in the hydrolysis of urea) contains nickel. The NiFe-hydrogenases contain nickel in addition to iron-sulfur clusters. Such [NiFe]-hydrogenases characteristically oxidise H
2. A nickel-tetrapyrrole coenzyme, Cofactor F430, is present in the methyl coenzyme M reductase, which powers methanogenic archaea.^[58] One of the carbon monoxide dehydrogenase enzymes consists of an Fe-Ni-S cluster.^[59] Other nickel-containing enzymes include a rare bacterial class of superoxide dismutase^[60] and glyoxalase I enzymes in bacteria and several parasitic eukaryotic trypanosomal parasites ^[61] (this enzyme in higher organisms, including yeast and mammals, uses divalent zinc, Zn²⁺).^{[62][63][64][65][66]}

Nickel can have an impact on human health through infectious diseases arising from nickel-dependent bacteria.^[67] Nickel released from Siberian Traps volcanic eruptions (site of the modern city of Norilsk) is suspected of having had a significant impact on the role played by Methanosarcina, a genus of euryarchaeote archaea that produced methane during the biggest extinction event on record.^[68]

§Toxicity

In the US, the minimal risk level of nickel and its compounds is set to 0.2 µg/m³ for inhalation during 15–364 days.^[69] Nickel sulfide fume and dust are believed carcinogenic, and various other nickel compounds may be as well.^[70][71] Nickel carbonyl, [Ni(CO)
4], is an extremely toxic gas. The toxicity of metal carbonyls is a function of both the toxicity of the metal as well as the carbonyl's ability to give off highly toxic carbon monoxide gas, and this one is no exception; nickel carbonyl is also explosive in air.^[72][73]

In the US, the Tolerable Upper Limit of dietary nickel is 1000 µg/day,^[74] while estimated average ingestion is 69-162 µg/day.^[75] Large amounts of nickel (and chromium) – comparable to the estimated average ingestion above – leach into food cooked in stainless steel. For example, the amount of nickel leached after 10 cooking cycles into one serving of tomato sauce averages 88 µg.^[76][77]

Sensitized individuals may show an allergy to nickel, affecting their skin, known as dermatitis. Sensitivity to nickel may also be present in patients with pompholyx. Nickel is an important cause of contact allergy, partly due to its use in jewellery intended for pierced ears.^[78] Nickel allergies affecting pierced ears are often marked by itchy, red skin. Many earrings are now made nickel-free due to this problem. The amount of nickel allowed in products that come into contact with human skin is regulated by the European Union. In 2002, researchers found amounts of nickel being emitted by 1 and 2 Euro coins far in excess of those standards. This is believed to be due to a galvanic reaction.^[79] Nickel was voted Allergen of the Year in 2008 by the American Contact Dermatitis Society.^[80]

Reports also showed that both the nickel-induced activation of hypoxia-inducible factor (HIF-1) and the up-regulation of hypoxia-inducible genes are due to depleted intracellular ascorbate levels. The addition of ascorbate to the culture medium increased the intracellular ascorbate level and reversed both the metal-induced stabilization of HIF-1- and HIF-1α-dependent gene expression.^[81][82]

Louis Pasteur

From Wikipedia, the free encyclopedia

Louis Pasteur
Photograph by Nadar
Born	(1822-12-27)December 27, 1822 Dole, France
Died	September 28, 1895(1895-09-28) (aged 72) Marnes-la-Coquette, France
Nationality	French
Fields	Chemistry Microbiology
Institutions	University of Strasbourg Lille University of Science and Technology École Normale Supérieure Pasteur Institute
Alma mater	École Normale Supérieure
Notable students	Charles Friedel[1]
Notable awards	Rumford Medal (1856, 1892) Copley Medal (1874) Albert Medal (1882) Leeuwenhoek Medal (1895)
Signature

Louis Pasteur (/ˈluːi pæˈstɜr/, French: [lwi pastœʁ]; December 27, 1822 – September 28, 1895) was a French chemist and microbiologist renowned for his discoveries of the principles of vaccination, microbial fermentation and pasteurization. He is remembered for his remarkable breakthroughs in the causes and preventions of diseases, and his discoveries have saved countless lives ever since. He reduced mortality from puerperal fever, and created the first vaccines for rabies and anthrax. His medical discoveries provided direct support for the germ theory of disease and its application in clinical medicine. He is best known to the general public for his invention of the technique of treating milk and wine to stop bacterial contamination, a process now called pasteurization. He is regarded as one of the three main founders of bacteriology, together with Ferdinand Cohn and Robert Koch, and is popularly known as the "father of microbiology".^[2][3][4]

Pasteur was responsible for crushing the doctrine of spontaneous generation. He performed experiments that showed that without contamination, microorganisms could not develop. Under the auspices of the French Academy of Sciences, he demonstrated that in sterilized and sealed flasks nothing ever developed, and in sterilized but open flasks microorganisms could grow. This experiment won him the Alhumbert Prize of the academy.^[5]

Pasteur also made significant discoveries in chemistry, most notably on the molecular basis for the asymmetry of certain crystals and racemization. He was the Director of the Pasteur Institute, established in 1887, till his death, and his body lies beneath the institute in a vault covered in depictions of his accomplishments in Byzantine mosaics.^[6]

Although Pasteur made groundbreaking experiments, his reputation became associated with various controversies. Historical reassessment of his notebook revealed that he practiced deception to overcome his rivals.^[7][8]

§Early life

The house in which Pasteur was born, Dole

Louis Pasteur was born on December 27, 1822, in Dole, Jura, France, to a Catholic family of a poor tanner. He was the third child of Jean-Joseph Pasteur and Jeanne-Etiennette Roqui. In 1827, the family moved to Arbois, where he entered primary school in 1831. He was an average student in his early years, and not particularly academic, as his interests were fishing and sketching. His pastels and portraits of his parents and friends, made when he was 15, were later kept in the museum of the Pasteur Institute in Paris. In 1838, he left for Paris to join the Institution Barbet, but became homesick and returned in November. In 1839, he entered the Collège Royal de Besançon and earned his baccalauréat (BA) degree in 1840. He was appointed teaching assistant at the Besançon college while continuing a degree science course with special mathematics. He failed his first examination in 1841. He managed to pass the baccalauréat scientifique (general science) degree in 1842 from Dijon but with a poor grade in chemistry. After one failed attempt for the entrance test for the École Normale Supérieure in Paris in 1842, he succeeded in 1844. In 1845 he received the licencié ès sciences (Bachelor of Science) degree. In 1846, he was appointed professor of physics at the Collège de Tournon at Ardèche, but Antoine Jérome Balard (one of the discoverers of the element bromine) wanted him back at the École Normale Supérieure as a graduate assistant (préparateur) for chemistry courses. He joined Balard and simultaneously started his research in crystallography and in 1847, he submitted his two theses, one in chemistry and the other in physics. After serving briefly as professor of physics at the Dijon Lycée in 1848, he became professor of chemistry at the University of Strasbourg, where he met and courted Marie Laurent, daughter of the university's rector in 1849.
They were married on May 29, 1849, and together had five children, only two of whom survived to adulthood; the other three died of typhoid. These personal tragedies were his motivations for curing infectious diseases.^[2][9]

§Professional career

Pasteur in 1857

Pasteur was appointed to the Chair of Chemistry in the faculty of sciences of the University of Strasbourg in 1848. In 1854, he was named dean of the new faculty of sciences at Lille University, where he began his studies on fermentation.^[10] It was on this occasion that Pasteur uttered his oft-quoted remark: "dans les champs de l'observation, le hasard ne favorise que les esprits préparés." (In the field of observation, chance favors only the prepared mind.^[11])

In 1857, he moved to Paris as the director of scientific studies at the École Normale Supérieure where he took control from 1858 to 1867 and introduced a series of reforms to improve the standard of scientific work. The examinations became more rigid, which led to better results, greater competition, and increased prestige. Many of his decrees, however, were rigid and authoritarian, leading to two serious student revolts. During "the bean revolt" he decreed that a mutton stew, which students had refused to eat, would be served and eaten every Monday. On another occasion he threatened to expel any student caught smoking, and 73 of the 80 students in the school resigned.^[12]

In 1862, he was appointed professor of geology, physics, and chemistry at the École nationale supérieure des Beaux-Arts, the position which held until his resignation in 1867. In Paris, he established the Pasteur Institute in 1887, in which he was its director for the rest of his life.^[3][4][9]

§Research contributions

§Molecular asymmetry

Pasteur separated the left and right crystal shapes from each other to form two piles of crystals: in solution one form rotated light to the left, the other to the right, while an equal mixture of the two forms canceled each other's effect, and does not rotate the polarized light.

In Pasteur's early work as a chemist, beginning at the École Normale Supérieure, and continuing at Strasbourg and Lille, he examined the chemical, optical and crystallographic properties of a group of compounds known as tartrates.^[13] He resolved a problem concerning the nature of tartaric acid (1848).^{[13][14][15][16][17]} A solution of this compound derived from living things (specifically, wine lees) rotated the plane of polarization of light passing through it. The mystery was that tartaric acid derived by chemical synthesis had no such effect, even though its chemical reactions were identical and its elemental composition was the same.^[18] Pasteur was able to show not only that optical activity related to the shape of the crystals, but also that an asymmetric internal arrangement of the molecules of the compound was responsible for twisting the light.^[10] The (2R,3R)- and (2S,3S)- tartrates were isometric, non-superposable mirror images of each other. This was the first time anyone had demonstrated molecular chirality, and also the first explanation of isomerism.^[13] Some historians consider Pasteur's work in this area to be his "most profound and most original contributions to science", and his "greatest scientific discovery."^[13]

§Fermentation and germ theory of diseases

Pasteur demonstrated that fermentation is caused by the growth of micro-organisms, and the emergent growth of bacteria in nutrient broths is due not to spontaneous generation, but rather to biogenesis (Omne vivum ex vivo "all life from life"). He was motivated to investigate the matter while working at Lille. In 1856 a local wine manufacturer, M. Bigot, the father of his student, sought for his advice on the problems of making beetroot alcohol and souring after long storage.^[19] In 1857 he developed his ideas stating that: "I intend to establish that, just as there is an alcoholic ferment, the yeast of beer, which is found everywhere that sugar is decomposed into alcohol and carbonic acid, so also there is a particular ferment, a lactic yeast, always present when sugar becomes lactic acid."^[20] According to his son-in-law, Pasteur presented his experiment on sour milk titled "Latate Fermentation" in August 1857 before the Société des Sciences de Lille. (But according to a memoire subsequently published, it was dated November 30, 1857).^[21][22] It was published in full form in 1858.^[23][24][25] He demonstrated that yeast was responsible for fermentation to produce alcohol from sugar, and that air (oxygen) was not required. He also demonstrated that fermentation could also produce lactic acid (due to bacterial contamination), which make wines sour. This is regarded as the foundation of Pasteur's fermentation experiment and disprove of spontaneous generation of life.

Pasteur experimenting in his laboratory.

Institut Pasteur de Lille

While Pasteur was not the first to propose the germ theory (Girolamo Fracastoro, Agostino Bassi, Friedrich Henle and others had suggested it earlier, with an experimental demonstration by Francesco Redi in the 17th century), he developed it and conducted experiments that clearly indicated its correctness and managed to convince most of Europe that it was true. Today, he is often regarded as the father of germ theory.^[26]

Pasteur's research also showed that the growth of micro-organisms was responsible for spoiling beverages, such as beer, wine and milk. With this established, he invented a process in which liquids such as milk were heated to a temperature between 60 and 100 °C.^[27] This killed most bacteria and moulds already present within them. Pasteur and Claude Bernard completed the first test on April 20, 1862.^[26] Pasteur patented the process, to fight the "diseases" of wine, in 1865.^[27] The method became known as pasteurization, and was soon applied to beer and milk.^[28]

Beverage contamination led Pasteur to the idea that micro-organisms infecting animals and humans cause disease. He proposed preventing the entry of micro-organisms into the human body, leading Joseph Lister to develop antiseptic methods in surgery. Lister's work in turn inspired Joseph Lawrence to develop his own alcohol-based antiseptic, which he named in tribute Listerine.^[29]

In 1865, two parasitic diseases called pébrine and flacherie were killing great numbers of silkworms at Alais (now Alès). Pasteur worked several years proving that these diseases were caused by a microbe attacking silkworm eggs, and that eliminating the microbe in silkworm nurseries would eradicate the disease.^[26]

Pasteur also discovered anaerobiosis, whereby some micro-organisms can develop and live without air or oxygen, called the Pasteur effect.

§Spontaneous generation

Bottle en col de cygne (swan neck duct) used by Pasteur

Following his fermentation experiments, Pasteur demonstrated that the skin of grapes was the natural source of yeasts, and that sterilized grapes and grape juice never fermented. He drew grape juice from under the skin with sterilzed needles, and also covered grapes with sterilized cloth. Both experiments could not produce wine in sterilized containers. His findings and ideas were against the prevailing notion of spontaneous generation. He received a particularly stern criticism from Félix Archimède Pouchet, who was director of the Rouen Museum of Natural History. To settle the debate between the eminent scientists, the French Academy of Sciences offered Alhumbert Prize carrying 2,500 francs to who ever could experimentally demonstrate for or against the doctrine.^[30][31][32]

To prove himself correct, Pasteur exposed boiled broths to air in swan-neck flasks that contained a filter to prevent all particles from passing through to the growth medium, and even in flasks with no filter at all, with air being admitted via a long tortuous tube that would not allow dust particles to pass. Nothing grew in the broths unless the flasks were broken open, showing that the living organisms that grew in such broths came from outside, as spores on dust, rather than spontaneously generated within the broth. This was one of the last and most important experiments disproving the theory of spontaneous generation for which Pasteur won the Alhumbert Prize in 1862. He concluded that:^[33][34]

Never will the doctrine of spontaneous generation recover from the mortal blow of this simple experiment. There is no known circumstance in which it can be confirmed that microscopic beings came into the world without germs, without parents similar to themselves.

§Immunology and vaccination

Pasteur's later work on diseases included work on chicken cholera. During this work, a culture of the responsible bacteria had spoiled and failed to induce the disease in some chickens he was infecting with the disease. Upon reusing these healthy chickens, Pasteur discovered he could not infect them, even with fresh bacteria; the weakened bacteria had caused the chickens to become immune to the disease, though they had caused only mild symptoms.^[2][26]

His assistant, Charles Chamberland (of French origin), had been instructed to inoculate the chickens after Pasteur went on holiday. Chamberland failed to do this, but instead went on holiday himself. On his return, the month-old cultures made the chickens unwell, but instead of the infections being fatal, as they usually were, the chickens recovered completely. Chamberland assumed an error had been made, and wanted to discard the apparently faulty culture when Pasteur stopped him. Pasteur guessed the recovered animals now might be immune to the disease, as were the animals at Eure-et-Loir that had recovered from anthrax.^[35]

In the 1870s, he applied this immunization method to anthrax, which affected cattle, and aroused interest in combating other diseases.

Louis Pasteur in his laboratory, painting by A. Edelfeldt in 1885

Pasteur publicly claimed he had made the anthrax vaccine by exposing the bacilli to oxygen. His laboratory notebooks, now in the Bibliothèque Nationale in Paris, in fact show that he used the method of rival Jean-Joseph-Henri Toussaint, a Toulouse veterinary surgeon, to create the anthrax vaccine.^[18][36] This method used the oxidizing agent potassium dichromate. Pasteur's oxygen method did eventually produce a vaccine but only after he had been awarded a patent on the production of an anthrax vaccine.

The notion of a weak form of a disease causing immunity to the virulent version was not new; this had been known for a long time for smallpox. Inoculation with smallpox was known to result in far less scarring, and greatly reduced mortality, in comparison with the naturally acquired disease. Edward Jenner had also discovered vaccination using cowpox to give cross-immunity to smallpox in 1796, and by Pasteur's time this had generally replaced the use of actual smallpox material in inoculation. The difference between smallpox vaccination and anthrax or chicken cholera vaccination was that the weakened form of the latter two disease organisms had been "generated artificially", so a naturally weak form of the disease organism did not need to be found. This discovery revolutionized work in infectious diseases, and Pasteur gave these artificially weakened diseases the generic name of "vaccines", in honour of Jenner's discovery. Pasteur produced the first vaccine for rabies by growing the virus in rabbits, and then weakening it by drying the affected nerve tissue.^[37]

The rabies vaccine was initially created by Emile Roux, a French doctor and a colleague of Pasteur who had been working with a killed vaccine produced by desiccating the spinal cords of infected rabbits. The vaccine had been tested in 50 dogs before its first human trial.^[38][39] This vaccine was first used on 9-year old Joseph Meister, on July 6, 1885, after the boy was badly mauled by a rabid dog.^[18][37] This was done at some personal risk for Pasteur, since he was not a licensed physician and could have faced prosecution for treating the boy. After consulting with colleagues, he decided to go ahead with the treatment. Three months later he examined Meister and found that he was in good health.^[40] Pasteur was hailed as a hero and the legal matter was not pursued. The treatment's success laid the foundations for the manufacture of many other vaccines. The first of the Pasteur Institutes was also built on the basis of this achievement.^[18]

Legal risk was not the only kind Pasteur undertook. In The Story of San Michele, Axel Munthe writes of the rabies vaccine research:

Pasteur himself was absolutely fearless. Anxious to secure a sample of saliva straight from the jaws of a rabid dog, I once saw him with the glass tube held between his lips draw a few drops of the deadly saliva from the mouth of a rabid bull-dog, held on the table by two assistants, their hands protected by leather gloves.

Because of his study in germs, Pasteur encouraged doctors to sanitize their hands and equipment before surgery. Prior to this, few doctors or their assistants practiced these procedures.

§Pasteur Institute

The Pasteur Institute was established by Pasteur to perpetuate his commitment to basic research and its practical applications. He brought together scientists with various specialties. The first five departments were directed by two normaliens (graduates of the École Normale Supérieure): Emile Duclaux (general microbiology research) and Charles Chamberland (microbe research applied to hygiene), as well as a biologist, Ilya Ilyich Mechnikov (morphological microbe research) and two physicians, Jacques-Joseph Grancher (rabies) and Emile Roux (technical microbe research). One year after the inauguration of the institute, Roux set up the first course of microbiology ever taught in the world, then entitled Cours de Microbie Technique (Course of microbe research techniques). Since 1891 the Pasteur Institute had been extended to different countries, and currently there are 32 institutes in 29 countries in various parts of the world.^[41]

§Faith and spirituality

His grandson, Louis Pasteur Vallery-Radot, wrote that Pasteur had only kept from his Catholic background a spiritualism without religious practice,^[42] although Catholic observers often said Louis Pasteur remained throughout his whole life an ardent Christian, and his son-in-law, in perhaps the most complete biography of Louis Pasteur, writes:

Absolute faith in God and in Eternity, and a conviction that the power for good given to us in this world will be continued beyond it, were feelings which pervaded his whole life; the virtues of the gospel had ever been present to him. Full of respect for the form of religion which had been that of his forefathers, he came simply to it and naturally for spiritual help in these last weeks of his life.^[43]

Maurice Vallery-Radot, grandson of the brother of the son-in-law of Pasteur and outspoken Catholic, also holds that Pasteur fundamentally remained Catholic.^[44] According to both Pasteur Vallery-Radot and Maurice Vallery-Radot, the following well-known quotation attributed to Pasteur is apocryphal:^[45] "The more I know, the more nearly is my faith that of the Breton peasant. Could I but know all I would have the faith of a Breton peasant's wife".^[2] According to Maurice Vallery-Radot,^[46] the false quotation appeared for the first time shortly after the death of Pasteur.^[47]
However, despite his belief in God, it has been said that his views were that of a freethinker rather than a Catholic, a spiritual more than a religious man.^[48][49][50] He was also against mixing science with religion.^[51][52]

§Principal works

Pasteur's principal works are:^[2]

French Title	Year	English Title
Etudes sur le Vin	1866	Studies on Wine
Etudes sur le Vinaigre	1868	Studies on Vinegar
Etudes sur la Maladie des Vers à Soie (2 volumes)	1870	Studies on Silk Worm Disease
Quelques Réflexions sur la Science en France	1871	Some Reflections on Science in France
Etudes sur la Bière	1876	Studies on Beer
Les Microbes organisés, leur rôle dans la Fermentation, la Putréfaction et la Contagion	1878	Microbes organized, their role in fermentation, putrefaction and the Contagion
Discours de Réception de M.L. Pasteur à l'Académie française	1882	Speech by Mr L. Pasteur on reception to the Académie française
Traitement de la Rage	1886	Treatment of Rabies

The standard author abbreviation Pasteur is used to indicate this individual as the author when citing a botanical name.^[53]

§Honours and final days

Pasteur was frequently struck by strokes since 1868, and the one in 1894 severely impaired his health. Failing to fully recover from the shock, he died in 1895, near Paris.^[18] He was given a state funeral and was buried in the Cathedral of Notre Dame, but his remains were reinterred in a crypt in the Pasteur Institute in Paris, where the crypt is engraved with his life-saving works.

He was awarded the prize of 1,500 francs in 1853 by the Pharmaceutical Society for the synthesis of racemic acid. In 1856 the Royal Society of London presented him the Rumford Medal for his discovery of the nature of racemic acid and its relations to polarized light, and the Copley medal in 1874 for his work on fermentation. The French Academy of Sciences awarded him the Montyon Prizes in 1859 for experimental physiology, and the Jecker Prize in 1861 and the Alhumbert Prize in 1862 for his experimental refutation of spontaneous generation. Though he lost election in 1857 for membership to the French Academy of Sciences, he won it in 1862 in mineralogy section, and was appointed to permanent secretary of the physical science section of the academy in 1887. In 1873 he was elected to the Académie Nationale de Médecine. He was elected to Littré's seat at the Académie française in 1881.

In 1873 he was made the commander in the Brazilian Order of the Rose.

Pasteur won the Leeuwenhoek medal, microbiology's highest Dutch honor in Arts and Sciences, in 1895. Both the Institute Pasteur and Université Louis Pasteur were named after him.

He was made a Chevalier or Knight of the Legion of Honour in 1853, promoted to Commander in 1868, to Grand Officer in 1878 and made a Grand Croix of the Legion of Honor – one of only 75 in all of France - in 1881.^[9]

On June 8, 1886, the Ottoman Sultan Abdul Hamid II awarded Pasteur with the Order of the Medjidie (I Class) and 10000 Ottoman liras.^[54]

§Legacy

Vulitsya Pastera or Pasteur Street in Odessa, Ukraine

In many localities worldwide, streets are named in his honor. For example, in the USA: Palo Alto and Irvine, California, Boston and Polk, Florida, adjacent to the University of Texas Health Science Center at San Antonio; Jonquière, Québec; San Salvador de Jujuy and Buenos Aires (Argentina), Great Yarmouth in Norfolk, in the United Kingdom, Jericho and Wulguru in Queensland, (Australia); Phnom Penh in Cambodia; Ho Chi Minh City; Batna in Algeria; Bandung in Indonesia, Tehran in Iran, near the central campus of the Warsaw University in Warsaw, Poland; adjacent to the Odessa State Medical University in Odessa, Ukraine; Milan in Italy and Bucharest, Cluj-Napoca and Timișoara in Romania. The Avenue Pasteur in Saigon, Vietnam, is one of the few streets in that city to retain its French name.

Avenue Louis Pasteur in the Longwood Medical and Academic Area in Boston, Massachusetts was named in his honor in the French manner with "Avenue" preceding the name of the dedicatee.^[55]

The Lycée Pasteur in Neuilly-sur-Seine, France, Lycée Louis Pasteur in Calgary, Canada and a large university hospital in Košice, Slovakia are also named after him.

His statue is erected at San Rafael High School in San Rafael, California.

A bronze bust of Pasteur resides on the French Campus of Kaiser Permanente's San Francisco Medical Center in San Francisco, California. The sculpture was designed by Harriet G. Moore and cast in 1984 by Artworks Foundry.^[56]

The UNESCO/Institut Pasteur Medal was created on the centenary of Pasteur's death, and is given every two years in his name, "in recognition of outstanding research contributing to a beneficial impact on human health".^[57]

§Controversies

A French national hero at age 55, in 1878 Pasteur discreetly told his family never to reveal his laboratory notebooks to anyone. His family obeyed and all his documents were held and inherited in secrecy. Finally in 1946 Pasteur's grandson and last surviving male descendant, Pasteur Valley-Radot donated the papers to the French national library (Bibliothèque nationale de France). Yet the papers were restricted for historical studies until the death of Valley-Radot in 1971. The documents were given catalogue number only in 1985. In 1995, the centennial of the death of Louis Pasteur, a historian of science Gerald L. Geison published an analysis of Pasteur's private notebooks in his "The Private Science of Louis Pasteur", and declared that Pasteur had given several misleading accounts and played deceptions in his most important discoveries.^[7][58] Max Perutz published a vigorous defense of Pasteur in the New York Review of Books.^[59] But further examinations of Pasteur's documents, such as by Patrice Debré in his book Louis Pasteur (1998),^[60] undeniably exposed the controversial natures of Pasteur's works. A French immnunologist, Debré admitted that in spite of his genius, Pasteur was sometimes unfair, combative, arrogant, unattractive in attitude, inflexible and even dogmatic.^[61]

§Fermentation

When Pasteur published his theory and experiments on fermentation in 1858, it was not new to science, neither the idea nor the experiment. In 1840 a German chemist Justus von Liebig had noted that yeast could induce fermentation in water. However, he did not know that yeasts were organisms. In 1856 another German Ludersdorrf reported that yeasts were microorganisms that convert sugar into alcohol.^[19] In 1855, Antoine Béchamp, Professor of Chemistry at the University of Montpellier, showed that sugar was converted to sucrose and fructose in a closed bottle containing water and when he added calcium or zinc chloride to it, no reaction occurred. He also noticed moulds developing in the solution, but could not fathom the significance of it. He concluded that water was the factor for fermentation.^[62] He changed his conclusion in 1858 that water was not the main factor, in fact, fermentation was directly related to the growth of moulds, and moulds required air for growth. He regarded himself as the first to show the role of microorganisms in fermentation.^[63] Pasteur started his experiments only in 1857 and published his findings in 1858 (April issue of Comptes Rendus Chimie, Béchamp's paper appeared in January issue), which, as Béchamp noted, did not bring any novel idea or experiments that earlier works had not shown. On the other hand, Béchamp was probably aware of Pasteur's 1857 preliminary works. With both scientists claiming priority on the discovery, a bitter and protracted dispute lasted throughout their lives. Their rivalry extended to ideas on microbiology, pathogenesis, and germ theory.^[64][65] Particularly on the spontaneous generation because Pasteur in his 1858 paper explicitly stated that the lactic acid bacteria (he named them "lactic yeasts"), which caused wine souring, "takes birth spontaneously, as easily as beer yeast every time that the conditions are favourable." This statement directly implied that Pasteur did believe in spontaneous generation. He condemned the ideas of Pasteur as "'the greatest scientific silliness of the age".^[20] However, Béchamp was on the losing side, as the BMJ obituary remarked: His name was associated with bygone controversies as to priority which it would be unprofitable to recall.^[66] Pasteur and Béchamp believed that fermentation was exclusively cellular activity, that is, it was only due to living cells. But later extraction of enzymes such as invertase by Marcelin Barthelot in 1860 showed that it was simply an enzymatic reaction.^[67]

§Anthrax vaccine

Pasteur had given a misleading account of the preparation of the anthrax vaccine used in the experiment at Pouilly-le-Fort.^[7] The fact is that Pasteur publicly claimed his success in developing anthrax vaccine in 1881.^[40] However, his admirer-turned-rival, a veterinarian Toussaint was the one who developed the first vaccine. Toussaint isolated the Gram-negative bacteria cholera des poules (later named – to add irony – Pasteurella in honour of Pasteur) in 1879 and gave samples to Pasteur who used for his own works. In 1880 with his publishing on July 12 at the French Academy of Sciences, Toussaint presented his successful result with an attenuated vaccine against anthrax in dogs and sheep.^[68] Pasteur purely on grounds of jealousy contested the discovery by publicly displaying his vaccination method in Pouilly-le-Fort on 5 May 1881. The promotional experiment was a success and helped Pasteur sell his products, getting all the benefits and glory.^[69][70][71]

§Experimental ethics

Pasteur experiments are often cited as against medical ethics, especially on his vaccination of Meister. Firstly, he did not have any experience in medical practice, and more importantly, a medical license. This is often cited as a serious threat to his professional and personal reputation.^[72][73] Even his closest partner Dr. Emile Roux refused to participate in the unjust clinical trial.^[74] But Pasteur executed vaccination of the boy under the close watch of practising physician Jacques-Joseph Grancher, head of the paediatric clinic at Paris Children's Hospital. He was even not allowed to hold the syringe, although the inoculations were entirely under his supervision.^[75] It was Grancher who was responsible for the injections, and defended Pasteur before the French National Academy of Medicine in the issue.^[76] Still giving someone a clinical test without proper diagnosis was unjustifiable. (Meister had not shown symptoms of rabies at the time.) Secondly, he kept secrecy of his procedure and did not give proper pre-clinical trials. But these accusations were not entirely correct. He disclosed his methods to a small group of scientists. Before using in human, he had successfully vaccinated 50 rabid dogs.^[77][78][79]