Maria Skłodowska-Curie (1867–1934)—her life and discoveries

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B. SkwarzecDecember 1898, the Curies and Bémont announced theexistence of another element, which they named “radium”for its intense radioactivity— a word that they coined [10].The discovery of radium was confirmed by spectroscopicanalysis of barium chloride salt [13]. Pitchblende is acomplex mineral and the chemical separation of its constituentswas an arduous task. The discovery of polonium hadbeen relatively easy; chemically it resembles the elementbismuth, and polonium was the only bismuth-like substance inthe ore. Radium, however, was more elusive [7]. It is closelyrelated, chemically, to barium, and pitchblende contains bothelements. By 1898–1899 Maria Skłodowska-Curie hadobtained traces of radium, but appreciable quantities, uncontaminatedwith barium, still were beyond reach [35]. Insubsequent years she undertook the arduous task of separatingradium salt by differential crystallization [16, 17]. From a tonof pitchblende, one-tenth of a gram of radium chloride wasseparated in 1902 [18]. In an unusual decision, MariaSkłodowska–Curie intentionally refrained from patentingthe radium-isolation process, so that the scientific communitycould do research unhindered [30]. Henri Becquereldiscovered radiation, but the discovery of radium initiatedscientific discussion about a new opinion on the atomicstructure. Maria and Pierre Curie formulated a hypothesisabout the atomic transformation of polonium and radium andreached the conclusion that the ability to radiate did notdepend on the arrangement of atoms in a molecule [11, 12,16]. Maria drew the conclusion that it must be linked to theinterior of the atom itself; this discovery was absolutelyrevolutionary [15].Maria’s doctoral thesisFrom 1900 Maria had a part-time teaching post at the ÈcoleNormale Superieur de Sevres for Girls [4]. After thousands ofcrystallizations she finally isolated one decigram of almostpure radium chloride and had determined radium’s atomicweight as 225. She presented the finding of this work in herdoctoral thesis. On 25 of June 1903, under the supervision ofHenri Becquerel, Maria was awarded her DSc from theUniversity of Paris for her thesis entitled “Recherches sur lessubstances radioactives” [28].The examination committee: Gabriel Lippmann, HenriMoissan, and Edmond Bouty, expressed the opinion thatthe findings represented the greatest scientific contributionever made in a doctoral thesis [4].Radiological health problemMaria and Pierre Curie were invited to the Royal Institution inLondon, and Pierre, before the crowded auditorium, showedhow radium rapidly affected photographic plates wrapped inpaper, how the substance gave off heat; in the semi-darknesshe demonstrated the spectacular light effect. He describedmedical tests which involved wrapping a sample of radiumsalts in a thin rubber covering which he had bound to his armfor ten hours. He then studied the resulting wound, which dayby day increasingly came to resemble a burn. After 52 days, apermanent grey scar appeared. Pierre realized the possibilityof radium being used in the treatment of cancers. Pierre’sscarred hands shook so much that once he happened to spill alittle of the preparation and fifty years later the presence ofradioactivity was discovered on the premises and theparticular surface had to be cleaned [4, 7].Nobel prizesIn 1903, the Royal Swedish Academy of Sciences awardedPierre Curie, Maria Curie, and Henri Becquerel the NobelPrize in Physics, “in recognition of the extraordinary servicesthey have rendered by their joint research on the radiationphenomena discovered by Professor Henri Becquerel [4].”Skłodowska–Curie and her husband were unable to go toStockholm to receive the prize in person, but they shared itsfinancial proceeds with needy acquaintances, includingstudents [30]. As a result of the Nobel Prize, Maria andPierre Curie suddenly became internationally famous. On 1October 1904, the Sorbonne gave Pierre a professorship andpermitted him to establish his own laboratory, in whichSkłodowska–Curie became the director of research. On 19April 1906, Pierre was killed in a street accident, he was runover by a horse-drawn wagon near the Pont Nuef in Paris[4]. Maria was devastated by the death of her husband, shewas left alone with two daughters, Irène aged 9 and Èveaged 2. Maria noted that, as of that moment she suddenlyhad become “an incurably and wretchedly lonely person”[7]. She was appointed to succeed Pierre as the head of thelaboratory, being undoubtedly the most suitable person, andto be responsible for his teaching duties. On 13 May 1906,the Sorbonne Physics department decided to retain the chairthat had been created for Pierre Curie and they entrusted it toSkłodowska–Curie together with full authority over thelaboratory. This allowed her to emerge from Pierre’s shadow[28]. On 16 November 1908, Maria was the first woman tobecome a professor at the Sorbonne, and in her exhaustingwork regime she sought a new meaning in her life [25]. Shewent on to produce four decigrams of very pure radiumchloride and determined radium’s precise atomic weight as226,45±0.5 (now 226.025) [19]. Finally, in collaborationwith Debierne, she was able to isolate radium in the metallicform [22]. At the same time Maria prepared new methods todetermine small amounts of radium by measurement ofradon [20, 23]. On September 1910, the International
Maria Skłodowska-Curie (1867–1934)Radiological Congress in Brussels invited Maria Curie toprepare international radium standards. In the next year MmeCurie delivered 21.99 mg of pure radium chloride to theBureau International des Poids et Mesures in Sevres [24]. ForMaria Curie, the proposal from the Radiological Congresscreated a new unit of radioactivity, the Curie (1 Ci isequilibrium with activity 1 g of radium). In 1911, MariaSkłodowska-Curie was awarded the Nobel Prize in Chemistry.The citation by the Nobel Committee was, “in recognitionof her services to the advancement of Chemistry by thediscovery of the elements radium and polonium; by theisolation of radium and the study of the nature andcompounds of this remarkable element” [4]. Maria’s Nobellecture on December 11 in Stockholm should be read in thelight of what she had gone through. She made it clear by herchoice of words what were unequivocally her contributions incollaboration with Pierre. She spoke of the field of researchwhich, “I have called radioactivity” and “my hypothesis thatradioactivity is an atomic property,” but without detractingfrom his contributions. She declared that she also regardedthis Prize as a tribute to Pierre Curie [7]. The Frenchgovernment funded the building of a private Radium Institute(Institut du Radium, now the Institut Curie), which was builtin 1914 and at which research in chemistry, physics, andmedicine was conducted [4]).Some researchers have questioned whether Maria deservedthe Prize for Chemistry in 1911 [27]. They have claimed thatthe discoveries of radium and polonium were part of thereason for the Prize in 1903, even though this was not statedexplicitly [15]. Maria was said to have been awarded thePrize again for the same discovery, the award possibly beingan expression of sympathy for reasons that will be mentionedlater [7]. Actually, however, the citation for the Prize in 1903was worded deliberately with a view to a future Prize inChemistry. Chemists considered that the discovery andisolation of radium was the greatest event in chemistry sincethe discovery of oxygen. For the first time in history it wasshown that an element could be transmuted into anotherelement, and that revolutionized chemistry and signified anew epoch [15].Skłodowska–Curie was the first person to win or sharetwo Nobel Prizes. She is one of only two people who havebeen awarded a Nobel Prize in two different fields, theother person being Linus Pauling (for chemistry and forpeace). Two Nobel Prizes have also been awarded to JohnBardeen in Physics (1956 and 1972) and Frederick Sangerin Chemistry (1958 and 1981).Rejected by the AcademyDespite the second Nobel Prize and an invitation to the firstSolvay Conference with the world’s leading physicists,including Einstein, Poincaré, and Planck, 1911 became a darkyear in Maria’slife[15]. In two smear campaigns she was toexperience the chauvinism of the French press. The firstcampaign was started on 16 November 1910, when, in anarticle in Le Figaro, it became known that she was willing tobe nominated for election to l’Académie des Sciences [4].Examples of factors other than merit influencing election tothe academy did exist, but Maria herself and her eminentresearch colleagues seemed to have considered that with herexceptionally brilliant scientific merits, her election was aforegone conclusion. As it turned out, it was not only meritthat was the deciding factor. The dark underlying currents ofanti-Semitism, prejudice against women, xenophobia, andeven anti-scientific attitudes that existed in French societycame welling up to the surface [15]. Normally the electionwas of no interest to the press. The most rabid paper was theultra-nationalistic and anti-Semitic L’Action Française,which was led by Léon Daudet, the son of the writerAlphonse Daudet. Dreyfus had obtained redress for thewrongs done to him in 1906 and had been decorated with theLegion of Honor, but in the eyes of the groups who had beenagainst him during his trial, he was still guilty, was still “theJewish traitor.” [4, 30]. The pro-Dreyfus groups who hadsupported his cause were suspect and the scientists who weresupporting Maria were among them. Jokes in bad tastealternated with outrageous accusations. It was said that in hercareer, Pierre’s research had given her a free ride. She camefrom Poland, though admittedly she was formally a Catholicbut her name Sklodowska indicated that she might be ofJewish origin, and so on. A week before the election, analternative candidate, Édouard Branly, was proposed. Thevote on January 23 1911 was taken in the presence ofjournalists, photographers, and hordes of the curious. Theelection took place in a tumultuous atmosphere. In the firstround Maria lost by one vote, in the second by two. In all,fifty-eight votes were cast [15]. A Nobel Prize in 1903 andsupport from prominent researchers such as Jean Perrin,Henri Poincaré, Paul Appell, and the permanent secretary ofthe Académie, Gaston Darboux, were not sufficient to makethe Académie open its doors. This event attracted internationalattention and indignation. It deeply wounded bothMaria and indeed Édouard Branly too, himself a wellmeritedresearcher [4].The Langevin AffairHowever, Maria’s tribulations were not at an end. When, atthe beginning of November 1911, Maria went to Belgium,being invited with the world’s most eminent physicists toattend the first Solvay Conference, she received a messagethat a new campaign had started in the press. Now it was amatter of her private life and her relations with her
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Maria Skłodowska-Curie (1867–1934)—her life and discoveries

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