Marie Curie and the History of Radioactivity

Pierre Curie met Marie Sklodowska when he was 35 years old and already an internationally recognised physicist. With his brother Paul-Jacques, he discovered piezo-electricity: the fact that crystals under pressure produce electric currents. He also studied crystal symmetries and the magnetic properties of bodies at different temperatures. His papers had been well received by distinguished colleagues but he was still an outsider in the French academic community. Like Marie he did not care for outward distinctions or a career. They married in July 1895.

Pierre followed his wife's work closely and he and his brother made her an electrometer which measured weak electrical currents, based on the piezo-electric effect. After the exciting results of Marie's early experiments Pierre abandoned his passionate study of crystals to join her in her search for new substances. He continued to construct pieces of laboratory equipment such as the ionisation chamber pictured below. Together they laboured Marie carrying out the chemical separations and Pierre taking the measurements. Together they discovered polonium and radium and used the word 'radioactivity' for the first time.

This sensitive device was developed by Pierre Curie for investigations into radioactivity. The chamber consists of a positive and negative plate connected by an electrometer. Radiation ionises the air in the chamber. The breakdown of air molecules into positive and negative ion pairs allows them to act as carriers of electric current. The negative ions migrate to the positive plate and the positive ions to the negative plate. This causes a weak electric current to flow which can be measured on the electrometer. The level of radioactivity will determine the strength of the current.

At a Royal Institution Lecture in London in 1903, Pierre described the amazing properties of radium and the medical tests he had been carrying out on himself. He had tied a piece of radium to his arm for ten hours and then studied the burn-like wound that left a permanent scar. Because of this, Pierre observed the potential of radium in treating cancer. In 1903 Marie and Pierre Curie were awarded half the Nobel Prize.

Irene Joliot-Curie ... was born in the stirring days of radioactivity when her parents [Marie and Pierre Curie] were making great discoveries, she grew up with radioactivity, and all her life was devoted to its study.'

'In 1926 she married Frédéric Joliot ... and there began a collaboration of husband and wife in scientific work rivalling in productive genius even that of her parents. The most outstanding of their joint papers were published in the years 1932-1934. In the first of these, on the radiation excited in beryllium by alpha-particles, they reported a very strange effect which provided the clue to the discovery of the neutron. Then, after studying the conditions of excitation of neutrons by the impact of alpha-particles on various elements, they turned for a time to the 'materialization' of positive electrons through the action of gamma-rays of high energy. This was followed by a systematic study of the radiations emitted from the lighter chemical elements under the impact of alpha-particles, which through the light of intuition - and good technique - led them, in early 1934, to their beautiful discovery of artificial radioactivity. An interesting feature of this discovery is that it was not so long in coming; the phenomenon of artificial activity had been expected, and sought for, since the earliest days of radioactivity. For this discovery the Joliot-Curies were awarded the Nobel Prize for Chemistry in 1935.' From her obituary by James Chadwick in Nature, 177, 964 (1956) Quote:- (Science Museum Library, 3 STS Pers 5 Nature Store Service QJN216)