A railwayman’s son in Paris and Meaux
Ferdinand Frédéric Henri Moissan was born in Paris on September 28, 1852. His family was modest. His father was a junior employee of the Eastern Railway Company and his mother was a seamstress. In 1864 the family moved to Meaux, east of Paris, where Henri went to the local collège and was apprenticed to a clockmaker, a training in fine, patient handwork that would later show in his laboratory.
The Franco-Prussian War of 1870 sent the family back to Paris. Moissan had not earned the school qualification needed to enter university, and his path into science was anything but straight. He served for a time in the army, then in 1871 began training in pharmacy. While working for a Paris pharmacist he helped save a man who had been poisoned with arsenic, an experience that turned his interest firmly toward chemistry.
A late start and a borrowed laboratory
Moissan studied first in the laboratory of the chemist Edmond Frémy at the Muséum d’Histoire Naturelle in Paris, then with the plant chemist Pierre Paul Dehérain at the École Pratique des Hautes Études. Dehérain persuaded him to aim for an academic career. Moissan passed the baccalauréat in 1874 on his second attempt, qualified as a first-class pharmacist in 1879 and received his doctorate in 1880 for work on cyanogen compounds. His first scientific paper, written with Dehérain in 1874, dealt with how leaves take in oxygen and give out carbon dioxide.
He moved steadily up through the Paris School of Pharmacy, becoming professor of toxicology in 1886 and taking its chair of inorganic chemistry in 1899. In 1900 he succeeded Louis Troost as professor of inorganic chemistry at the University of Paris, the Sorbonne. Yet the work that made his name was done before he had a proper laboratory of his own. In the 1880s he borrowed bench space and equipment from senior colleagues, among them the chemist Charles Friedel.
Taming the “savage beast” among the elements
Chemists had known for decades that the mineral fluorspar and hydrofluoric acid must contain a new element, fluorine, closely related to chlorine and iodine. But every attempt to free it had failed, and several experimenters had been injured or killed by the poisonous, corrosive substances involved. The difficulty, as the Swedish Academy later explained, was double. Fluorine is so reactive that it attacks almost everything it touches, even water, and the obvious starting material, pure liquid hydrogen fluoride, does not conduct electricity, so it cannot simply be split with a current.
Moissan turned to fluorine chemistry in 1884. He discovered that dissolving potassium fluoride in liquid hydrogen fluoride produced a mixture that stayed liquid and conducted electricity at temperatures well below freezing. He built an apparatus with electrodes of platinum and iridium, the few materials that could survive, held in a platinum vessel and cooled to about minus 50 degrees Celsius. On June 26, 1886, he passed a current through the mixture and collected hydrogen at one electrode and, for the first time, pure fluorine gas at the other.
When a commission of the French Academy of Sciences came to watch, the demonstration failed: his newly purified hydrogen fluoride lacked the trace of potassium fluoride that had made it work. Moissan found the problem, repeated the experiment successfully, and won the Academy’s prize. He went on to study the new element’s reactions with almost every other element, and with Paul Lebeau he prepared sulphur hexafluoride in 1901. His method, electrolysis of potassium fluoride dissolved in hydrogen fluoride, is still the basis of the way fluorine is produced commercially today.
Why fluorine matters to everyday life
Isolating fluorine opened the door to one of the most useful branches of modern chemistry. Elemental fluorine and its compounds became essential to the twentieth century in ways Moissan could not have imagined. The largest use of fluorine gas is to make uranium hexafluoride, the compound used to enrich uranium for the fuel of nuclear power stations. Carbon and fluorine form one of the strongest bonds in chemistry, and that strength gave the world non-stick and chemically resistant plastics such as Teflon, refrigerant gases for fridges and air conditioning, and sulphur hexafluoride, the gas used to insulate high-voltage electrical equipment.
Fluorine compounds also became important in medicine and health. Many modern medicines contain fluorine atoms, which change how a drug behaves in the body, and fluoride salts in toothpaste and drinking water help prevent tooth decay. Some fluorine chemistry has also caused harm: certain refrigerants damaged the ozone layer and were phased out, and some long-lived fluorinated chemicals are now a serious environmental concern. Both the benefits and the problems flow from the chemistry that became possible once Moissan showed how to make and handle the element.
The electric furnace
Moissan’s second great achievement grew from a dream of making diamonds. In 1892 he theorized that diamonds might crystallize from carbon dissolved in molten iron under pressure. To reach the heat he needed, he designed and developed an electric arc furnace that reached temperatures of up to about 3,500 degrees Celsius, far hotter than any ordinary furnace. He reported tiny artificial stones, though later scientists doubted that they were true diamonds.
The furnace itself proved far more important than the diamonds. With it Moissan melted and vaporized substances that had been regarded as impossible to melt, and prepared many new compounds, especially carbides, silicides and borides. He made pure calcium carbide, the starting point for acetylene gas, and he obtained metals such as tungsten, molybdenum and titanium in solid, pure form for the first time. At the 1906 Nobel ceremony the president of the Swedish Academy said that the furnace had given technology an impetus whose effects could not yet be measured. Electric arc furnaces became a pillar of heavy industry, and today they are widely used to make steel from recycled scrap.
His curiosity reached even to the stars. In 1893 he examined fragments of the meteorite that formed Meteor Crater in Arizona and found a new mineral, a natural silicon carbide. It was named moissanite in his honour in 1905. Moissan also served from 1903 on the International Atomic Weights Committee and wrote more than three hundred publications, including major books on the electric furnace and on fluorine and its compounds.
Jewish heritage
Moissan’s Jewish heritage came through his mother. Sources describe him as the son of a non-Jewish father and a Jewish mother, and the Jewish Virtual Library counts him as the second Jewish Nobel laureate in history, after Adolf von Baeyer. He was not raised in the Jewish community. He practised the Catholic faith, and there is no record that he identified with Judaism.
He lived and worked in a France where Jewish origins could still be a political issue, in the years of the Dreyfus affair, but there is no evidence that antisemitism shaped his own career, which was built inside the French scientific establishment.
Teacher, colleague and family man
Moissan was known as an excellent lecturer and a meticulous, patient experimentalist, the clockmaker’s apprentice never quite gone from his hands. He was elected to the French Academy of Medicine in 1888 and to the Academy of Sciences in 1891, became a commander of the Legion of Honour, and received the Davy Medal of the Royal Society of London in 1896. In 1882 he married Léonie Lugan; their son, Louis, was born in 1885. In Paris he counted the chemist Alexandre Léon Étard among his close friends.
His public service reflected his training as a pharmacist and toxicologist. He sat on the Seine department’s council of public hygiene from 1895 and on France’s advisory committee for arts and manufactures from 1898, bodies that advised on health and industry. Beyond fluorine and the furnace, his laboratory prepared the hydrides of calcium, sodium and potassium, isolated many metals, and studied carbides so closely that he proposed some petroleum might form underground from the reaction of carbides with water. Between 1904 and 1906 he edited a five-volume treatise on inorganic chemistry that summed up the field for a generation of students.
Working with fluorine took a toll. Moissan was poisoned more than once during his experiments, and he worked for years with toxic gases including carbon monoxide. Colleagues admired the courage as much as the skill: at the Nobel ceremony he was praised for the great experimental skill with which he had isolated and studied the most violent of the elements.
A sudden death and a lasting legacy
In December 1906 Moissan travelled to Stockholm to receive the Nobel Prize in Chemistry, awarded for isolating and investigating fluorine and for bringing the electric furnace into the service of science. Shortly after he returned to Paris he fell ill, and he died suddenly on February 20, 1907, at the age of 54. His death was attributed to acute appendicitis; some historians have suggested that years of exposure to fluorine and carbon monoxide may have weakened him.
His legacy is enormous and mostly invisible. Fluorine is still made commercially by the electrolytic method he devised. The electric arc furnace he pioneered is a mainstay of modern steelmaking and materials production. And the chemistry of fluorine, which he was the first to explore in pure form, now runs through nuclear energy, electronics, medicines, plastics and refrigeration.
Sources & further reading
Henri Moissan, Biographical, NobelPrize.org · Award ceremony speech, Nobel Prize in Chemistry 1906, NobelPrize.org · Henri Moissan, Jewish Virtual Library · Henri Moissan, Wikipedia · Fluorine, Wikipedia · Researched from the sources above and checked against them. Spotted an error? Tell us.
A life of tikkun olam. This is part of tikkun olam, the Jewish idea of repairing the world, and every one of us can add to it.