Thinkers Timeline

Jabir ibn Hayyan (c.721-815 CE), known in medieval Europe as Geber, was a scholar of the early Islamic world whose writings on alchemy, chemistry, pharmacy, and metallurgy laid much of the practical foundation of chemical knowledge. His life is poorly documented and many details are uncertain. He is traditionally said to have been born in Tus in Khurasan, in what is now northeastern Iran, to an Arab family of the Azd tribe, and to have worked at the Abbasid court in Baghdad and Kufa under the patronage of the Barmakid family, the powerful viziers of the Caliph Harun al-Rashid. When the Barmakids fell from favour in 803, Jabir reportedly retreated from public life. The scale of the writings attributed to him — several thousand treatises — is far larger than any single person could have produced, and modern scholars now believe that many works under his name were written over two or three centuries by a group of scholars associated with a particular religious and philosophical tradition, possibly the Ismaili branch of Shia Islam. Whether Jabir was a single historical person who founded the tradition, a legendary name used by later writers, or both at once, the Jabirian corpus represents one of the richest bodies of alchemical and chemical writing ever produced. It was translated into Latin from the twelfth century onwards and shaped European alchemy, through which it helped seed the eventual emergence of modern chemistry.

Antoine-Laurent de Lavoisier (1743-1794) was a French chemist whose systematic use of the balance to measure the weights of substances before and after chemical reactions helped transform chemistry from a largely qualitative study into a quantitative science. He was born in Paris to a wealthy bourgeois family, studied law in accordance with his family's wishes, and then turned to science. He was elected to the Academy of Sciences at twenty-five. To fund his expensive experimental work he became a member of the Ferme generale, the private tax-collecting consortium that gathered certain taxes for the French crown — a position that gave him income and later cost him his life. In 1771 he married Marie-Anne Paulze, fourteen years his junior, who became his essential scientific collaborator, translating English papers into French, drawing apparatus, and keeping laboratory records. Through the 1770s and 1780s Lavoisier carried out meticulous experiments on combustion, calcination, and respiration, eventually showing that combustion was reaction with a component of air he called oxygene. He proposed a new chemical nomenclature and published Traite elementaire de chimie in 1789, widely regarded as the first modern chemistry textbook. In the French Revolution, his membership of the tax farm became a mortal liability. He was arrested, tried, and guillotined in 1794 at fifty, along with twenty-seven other former tax collectors. The mathematician Lagrange remarked the next day: it took them only an instant to cut off that head, and a hundred years may not be enough to produce another like it.

Dmitri Ivanovich Mendeleev (1834-1907) was a Russian chemist who devised the periodic table of the elements, one of the most important organising schemes in the history of science. He was born in Tobolsk, Siberia, the youngest of what may have been as many as seventeen children. His father, a teacher of philosophy and literature, went blind and then died when Dmitri was still young; his mother kept the family going by running a glass factory. When the factory burned down, she travelled more than two thousand kilometres by horse and cart to take her gifted youngest son to St Petersburg, where she eventually placed him in what became his university. He completed his studies there and went on to postgraduate research in Heidelberg and Paris before returning to teach in St Petersburg. In 1869, while preparing a chemistry textbook, he arranged the known chemical elements in order of atomic weight and noticed that their properties repeated at regular intervals. He published his first periodic table that year. The table left gaps for elements he predicted would be discovered, with detailed forecasts of their properties; when gallium, scandium, and germanium were found in the following decades and matched his predictions, the table's power became undeniable. Mendeleev was also a practical scientist who worked on Russian oil production, agriculture, metrology, and economics. He never received the Nobel Prize, despite being nominated. He died in St Petersburg in 1907.

Percy Lavon Julian (1899-1975) was an African American chemist whose pioneering synthesis of plant-derived steroids made cortisone and other hormone-based medicines widely available for the first time. He was born in Montgomery, Alabama, the grandson of former slaves. Alabama's public schools did not offer education beyond the eighth grade to Black children at the time, but his parents — a railway mail clerk and a teacher — insisted on his further education. He entered DePauw University in Indiana as what the institution called a sub-freshman, taking high school classes alongside his college studies, and graduated as valedictorian in 1920. American graduate programmes in chemistry were largely closed to Black students; he was refused admission at several top universities and taught for several years at historically Black colleges before winning a fellowship for graduate work at Harvard. Harvard gave him a master's degree but denied him the chance to teach or to complete a doctorate because of his race. He eventually earned his doctorate in Vienna in 1931, one of the few options then available. In 1935 he completed the total synthesis of the alkaloid physostigmine, used to treat glaucoma, beating a competing English group. Unable to get university chemistry positions because of his race, he joined the Glidden Company, a paint manufacturer, where he led research that developed industrial methods for producing steroids from soybean oil — processes that made cortisone affordable to patients with rheumatoid arthritis and opened the way to a generation of hormone-based medicines. He later founded his own company. He and his family faced racist violence in the Chicago suburb where they bought a house in 1950, including attempts to burn and bomb their home. He died in 1975. He was elected to the National Academy of Sciences in 1973, the second African American so honoured.

Dorothy Crowfoot Hodgkin was an English chemist. She remains the only British woman ever to win a Nobel Prize in any of the sciences. She was born on 12 May 1910 in Cairo, Egypt, where her father worked for the British colonial education service. The family later moved to Sudan. As a young child, Dorothy and her sisters were sent to live with relatives in England while her parents stayed in North Africa. She loved crystals from age ten, when she made her first crystals from chemistry kits. She was one of only two girls allowed to study chemistry at her school in Suffolk, where the subject was thought to be for boys. She studied chemistry at Somerville College, Oxford, from 1928 to 1932. She then went to Cambridge for her PhD with the crystallographer J. D. Bernal. In her mid-twenties she developed serious rheumatoid arthritis, which would deform her hands and feet for the rest of her life. She kept working anyway. She returned to Oxford in 1934 and worked there for the rest of her career. In 1937 she married Thomas Hodgkin, a historian who became an authority on African history. They had three children. She spent decades working out the three-dimensional structures of complicated biological molecules using X-ray crystallography. She solved the structure of penicillin in 1945, vitamin B12 in 1955, and finally insulin in 1969, after working on it for thirty-four years. She won the Nobel Prize in Chemistry in 1964. She died on 29 July 1994, aged 84.

Rosalind Franklin (1920-1958) was a British chemist and X-ray crystallographer. She was born in London into a prominent Jewish family and showed exceptional scientific ability from childhood. She studied chemistry at Cambridge University and then worked in Paris, where she became expert in X-ray crystallography: a technique that uses X-rays to determine the three-dimensional structure of molecules. She returned to England in 1951 to work at King's College London, where she was assigned to study the structure of DNA. Working with extraordinary precision, she produced some of the clearest X-ray photographs of DNA ever taken, including the famous Photo 51, which showed clear evidence of the double-helix structure. This photograph was shown to James Watson without her knowledge or permission by her colleague Maurice Wilkins. Watson and Francis Crick, who also had access to Franklin's unpublished data through other channels, used this information to build their model of DNA. Their paper announcing the double-helix structure was published in Nature in April 1953. Franklin was not credited as a contributor. She went on to do brilliant work on the structure of viruses at Birkbeck College before dying of ovarian cancer in 1958 at the age of thirty-seven. Watson, Crick, and Wilkins received the Nobel Prize for the discovery of DNA's structure in 1962.