The gifted crystallographer
Name: Ellen Gleditsch
Claim to fame: Established half-life of radium and confirmed existence of isotopes
Ellen Gleditsch (1879-1968), who established the half-life of radium and confi rmed the existence of isotopes, was one of the first specialists in radiochemistry. As a gifted crystallographer, she made important contributions to science in the laboratory of Marie Curie-Skłodowska.
Learning before all else
Born in Norway in 1879, Ellen was the oldest of 11 children. Her father, a natural history teacher, and her mother, an intellectual and advocate of women’s rights, made sure that their children were all exposed to cultural, musical, and natural activities in addition to their regular schooling. Supported by a family that valued education above all else, Ellen became valedictorian of her high-school class in southern Norway. She then went on to train as a pharmacologist in the northern city of Tromsø in 1902. (The first woman had entered university in Norway in 1882.)
In 1903, Gleditsch was invited to study in the laboratory of chemist Eyvind Bødtker at the University of Oslo and soon became his assistant. In 1905, she passed the university’s entrance exam and, at the suggestion and with the support of Bødtker, continued her investigations in Paris in the laboratory of Marie Curie-Skłodowska in 1907. (Curie had earned a Nobel Prize for her work in radioactivity only a few years earlier.) This proved to be an important decision, as Ellen contributed in no small way to the cutting-edge science produced by that small group.
In the 1930s, Ellen helped to plan and eventually directed, a radiochemistry laboratory in Norway. When the Nazis came to power in Germany, she offered the laboratory as a ‘safe-house’ for scientists fleeing persecution. During the occupation in the 1940s, she continued her experiments and worked underground, hiding people in her home and going undercover as a needle worker to relay messages about the movement. Following a raid on her laboratory in 1943, during which all of the men were arrested, Ellen and the other women scientists cleared the lab of valuable radioactive minerals. She hid them in a suitcase under her bed.
The Curie years
Ellen proved an invaluable asset to the laboratory of Marie Curie, performing ‘fractional crystallisations‘, a difficult technique in which few scientists were competent, to purify radium. For this work, her laboratory fees were waived. She worked closely with Marie for fi ve years analysing uranium and radium in radioactive minerals, and after leaving the laboratory she returned several times to supervise experiments.
Ellen received a Licenciée en sciences degree from the Sorbonne in 1911 and that same year was awarded a teaching fellowship at the University of Oslo. After a year in the Norwegian capital, she won a scholarship from the American- Scandinavian Foundation (the first such scholarship given to a woman) to study in the United States, and she jumped at the chance. She wrote to two prestigious scientists in the US asking to work in their laboratories but was turned down, in one case on the basis of her gender.
Measuring a half-life
She went to Yale University despite having been rebuffed, bringing with her two of her brothers as her parents had both recently died. She spent a year completing her research into the half-life of radium (the amount of time it takes for half of the radioactive atoms in a sample of radium to decay) and established it as 1 686 years, which remained the standard for many years before being corrected to 1 620 years.
Ellen‘s measurement paved the way for several important discoveries, as the half-life of radium could be used as a benchmark for studying the radiochemistry of other elements. The scientists who had turned her down changed their minds about having women in their laboratories, and one of them became co-author of two of her articles. In June 1914, she received an honorary doctorate for her work in radioactivity from Smith College in Northampton, Massachusetts.
Supporting her fellow scientists
Ellen returned to the University of Oslo in 1914, and in 1917 became the second woman to be elected to Oslo‘s Academy of Science. Twelve years later, after an arduous appointment procedure, she became the second woman to receive a full professorship from the university. A fervent supporter of women in science throughout her career, she co-founded the Norwegian Women Academics Association in 1919 and, from 1926 to 1929, served as president of the International Federation of University Women, a position that allowed her to travel and lecture extensively.
Ellen was charming and pleasant, and made friends easily. She built up an impressive network of international contacts, both professional and personal, during the course of her career. During her retirement, Ellen continued to publish papers and to advise students. Following her death from a stroke in 1968, the Ellen Gleditsch Scholarship Foundation was established in Norway to support aspiring scientists.
Ellen Gleditsch is regarded as an important link between several prominent groups in radioactivity in Europe and the US. Her most celebrated scientific achievement was her work on the half-life of radium. But she also played a major role in confirming the existence of isotopes (types of atoms of the same element that have different atomic mass). When a British chemist‘s claim that an element‘s atoms could have different atomic weights was largely dismissed, Ellen, along with many researchers, sent a sample of lead that she had purifi ed to a leading researcher in the United States. Her sample was the only one pure enough to prove the existence of isotopes.