Chapter Fourteen

SUZANNE (Platinum and Iridium)

SUZANNE VEIL, a native Parisian of twenty-six years, arrived at the Sorbonne Annex at the start of the fall term in 1912, expecting to gain experience in radioactivity under Madame’s guidance. Faced with the reality of the director’s ongoing absence, however, Mlle. Veil sidled instead into the chemistry laboratory of Georges Urbain, an expert on the rare earths—a group of fifteen closely related metallic elements.

For the first time since the establishment of the Laboratoire Curie, no women were to be seen working there, not even Marie. Her convalescence stretched through the autumn and into the winter.

When at last she set out, on the morning of February 21, 1913, on her first official errand after the long illness, she traveled across town with André Debierne to deposit her precious radium standard at the Bureau International des Poids et Mesures (BIPM). The bureau, which was home to the Metre and the Kilogram, stood next door to the school at Sèvres where she had taught her first physics classes. The sight of the towering chestnut trees in the Parc de Saint-Cloud welcomed her back to familiar ground. At the same time, the choice of the bureau as repository appeased the foreign members of the radium-standard committee, who had bristled at the thought of allowing the international standard to be kept in Mme. Curie’s lab. To them, the BIPM represented neutral territory with global recognition. And although it was certainly true that the bureau wielded worldwide authority, Marie had finessed the radium arrangement through her personal rapport with its deputy director, Charles-Édouard Guillaume, an old and trusted friend of Pierre’s.

Guillaume stipulated that the radium standard be stored unofficially, because the bureau owned no in-house expertise in radioactivity. Guillaume himself specialized in metal alloys, such as the combination of platinum and iridium that composed the international prototypes of the Metre and Kilogram. These two priceless objects, along with six exact copies of each, resided in an underground vault with a triple-locked, double-iron door. The radium standard would be kept in a separate safe, located one floor up from the platinum-iridium prototypes, among other duplicates of them. Of course, the BIPM could not be held responsible in the event that any misfortune, such as fire or theft, befell the radium standard. Therefore, the less said about the matter, the better. As agreed upon in advance, no publicity or ceremony attended the moment when the radium standard, sealed in its small glass tube and packed in a protective metal box, left Marie’s hands to take its newly assigned place on a shelf inside the designated safe, to which Guillaume held the only key.

Marie’s compensation for the expense of fabricating the standard had likewise come about unofficially, through personal contacts. When the question of cost first arose, at the 1910 congress in Belgium, Ernest Rutherford had thought of appealing to government stakeholders for funding. Going that route, however, would have invited the intrusion of government bureaucrats into the committee’s doings, and so Rutherford urged the members to seek other sources of financial support. In 1912 Frederick Soddy’s wealthy father-in-law, the industrial chemist George Beilby of Glasgow, agreed to reimburse Mme. Curie for the radium invested in her standard. In return, she publicly thanked “Dr. and Mme. Beilby” in an article for the Journal de physique.

Responsibility for producing the secondary standards fell to the Radium Institute of Vienna, which could tap the rich pitchblende source of the St. Joachimsthal mine. The secondaries were to contain smaller quantities of radium than the international standard, and thus would be less costly to produce, but comparably pure. Once they passed muster, the secondaries would be distributed for local use in Germany, the United Kingdom, the United States, and beyond—wherever radioactivity research took root.

Having duly delivered the radium standard to the BIPM in February, Marie returned to retrieve it just a few months later, in May. The first of the secondary standards had arrived from Vienna, bound for the National Physical Laboratory in England. She performed the necessary tests at her lab, which she had lately taken to calling the Paris Laboratory of Radioactivity. The comparison tests involved quantifying the secondary’s radioactive emissions over a period of weeks by measuring its gamma radiation via electroscope. She then signed a certificate of authenticity and took the international standard back to Sèvres, where it would remain until she needed to borrow it again.

The Curie lab had been acting as a de facto measurement service almost since the discovery of radium. Pierre and Marie had personally set the standards for the French radium industry when they gave Armet de Lisle’s Sels de Radium the Curie seal of approval. In recent years Marie had also been called upon to certify the output of two additional French radium factories, as well as the radioactive products employed at various hospitals and doctors’ offices. Providing this service struck her as such a crucial activity that she had written it into her plans for the new radium institute now under construction. Meanwhile she carried on the measurement work as professionally and efficiently as possible. Each time a request reached the Curie lab, she complied in order to validate the radioactive sample in question—and never to advance one individual’s or institution’s interests over another’s. The fee she charged in exchange for the time she or André Debierne devoted to these efforts defrayed some of their other expenses. Under no circumstances did she permit anyone whose products earned a Curie-lab certificate to tout that fact in commercial advertisements.

Despite her scrupulous handling of these matters, she fell afoul of Sorbonne rector Louis Liard, who accused her of commercialism and of acting without proper authorization from the Faculty of Science. Marie retorted that her certification was sought because of her personal expertise, not her affiliation with the university, and furthermore that she did the work for the public good, accepting payment only for the time spent. As for the granting of signed certificates, which particularly rankled Liard, she argued that she could not guarantee the specifics of her detailed analysis with a simple handshake. A formal investigation headed by Georges Urbain exonerated her of any misdeed.

Slowly she revived her research, beginning with a review of the extreme-low-temperature studies she had undertaken with Heike Kamerlingh Onnes. Although their collaboration at Leyden had ended in July 1911, they had held off publication all this time in the hope of extending their experiments. “But,” they explained in their 1913 coauthored report, “as the continuation of the work has been prevented so far by the long indisposition of one of us, we thought it best not to wait any longer in publishing our results.” As far as they could tell, extreme cold exerted no effect on radium’s characteristic behavior.

MADAME’S PROTÉGÉE Ellen Gleditsch, while striving to awaken Norwegian national interest in radium, suffered a devastating series of personal losses in the early months of 1913. First her mother, Petra Brigitte Hansen Gleditsch, died of tuberculosis in February. Then her brother August returned from engineering school in Germany, sick and dying of the same disease. Within weeks, their father, Karl Kristian Gleditsch, also succumbed to tuberculosis.

At the time of the family’s great hardship, all of Ellen’s surviving siblings had reached maturity except for the youngest one, eleven-year-old Kristian. Ellen, now thirty-two, instantly assumed responsibility for the boy’s care. Her sister Birgit, the second oldest, might have been willing to assist her but had married a missionary and gone with him to China. Ellen found a new apartment in the capital, large enough for herself, Kristian, and their brother Adler, age twenty. On her meager salary as an instructor, she accepted the burdens of marriage and motherhood without the benefit of a husband. “Fortunately,” Marie consoled her in a sympathy note, “I know you are strong and courageous and able to overcome your suffering by thinking of those who need you.”

Hiking in Switzerland: Miss Manley (the governess) in front with Ève Curie and Hans Einstein; at back, Albert Einstein, Marie Curie, and Irène Curie.

Musée Curie (coll. ACJC)

Marie tested her own strength and courage that summer by taking Irène and Ève on a walking tour through the Alpine valleys of the Engadin in southeastern Switzerland. There they hiked daily with Albert Einstein and his son Hans. She had not seen Einstein since meeting him at the Solvay Council in Brussels, where they had had time to become friendly just before she became a victim of the press. “I am so enraged by the base manner in which the public is presently daring to concern itself with you,” he wrote her from Prague in November 1911, “that I absolutely must give vent to this feeling.” Dismissing the lurid news reports as an attempt by the “rabble” to “satiate its lust for sensationalism,” he said, “I am impelled to tell you how much I have come to admire your intellect, your drive, and your honesty, and that I consider myself lucky to have made your personal acquaintance in Brussels.” He was “certainly happy,” he added, “that we have such personages among us as you, and Langevin too, real people with whom one feels privileged to be in contact.”

On their mountain walks the two physicists lagged behind the youngsters, parsing topics of mutual interest in a mixture of German and French. Ève later recalled howling with laughter at odd snippets of the grown-up conversation. She swore she and Irène heard Einstein tell their mother, “You understand, what I need to know is exactly what happens to the passengers in an elevator when it falls into emptiness.”

Although the recent past had been a fallow period for Marie, she had followed the research activities of all her colleagues. Einstein was expanding his theory of relativity. Rutherford’s experiments with alpha particles had revealed the structure of the atom. To his and others’ great surprise, the positively charged particles clumped together at the center, ringed at a distance by the negatively charged electrons. Rutherford called the central mass the “nucleus,” a term he borrowed from cell biology.

The atom’s exterior electrons conducted the ordinary business of chemistry, namely combining with other atoms. Radioactivity happened inside the nucleus, where, at any moment, the sudden, violent expulsion of a nuclear particle would convert an atom of one element into an atom of another.

These infinitely small-scale events exerted vast influence. According to the latest calculations, the heat released in radioactive decay warmed the whole Earth from within. Geologists had thought the Earth to be steadily cooling since the time of its formation, and feared its frozen demise within a few millennia. But radioactivity projected the planet’s life expectancy far into the future, and by the same token pushed its antiquity farther back into the past. Rocks dated by the new technique of measuring the proportion of uranium to lead showed themselves to be amazingly ancient. The estimated age of the Earth jumped from a few tens of millions of years to several billion.

By 1913 the radioactivity community recognized three distinct series, or “families,” of radioelements, each with its own pedigree. Radium belonged to the uranium ancestral line, or “uranium family,” distinct from the “thorium family” and the “actinium family.” A tally of all the decay products in all three lines of descent added up to thirty-four radioelements, all vying for barely one-third that number of vacant places on the periodic table between uranium, where radioactivity began, and lead, where radioactive decay ended. The superabundance of intervening substances threatened to topple the table. In an attempt to restore order, Frederick Soddy and others pointed out that several radioelements resembled one another too closely to be considered discrete elements. They were more like variations on a theme. Although they differed in their radioactivity, with different emissions and different half-lives, they behaved identically in chemical reactions. Once mixed together, they could not be parted from one another by any known means. Even their spectra looked identical. Since they were chemically the same, Soddy argued, they could share the same location on the periodic table. He was holding forth about these “chemically non-separable radioelements” one evening at the home of his in-laws, the Beilbys, when another dinner guest, the Glaswegian medical doctor and novelist Margaret Todd, coined a word to describe such chemical look-alikes. “Isotope,” she suggested, from the Greek for “same place.”

Isotopes relieved the immediate space problem on the periodic table. They also hinted at a deeper truth underlying the table’s organization. Mendeleev had relied on atomic weight as his guiding principle, arranging the elements in ascending order accordingly. But the fact that each isotope bore a slightly different atomic weight suggested that something other than weight—something even more fundamental—must serve as an element’s key defining feature. No one could say what that distinction might be.

To account for the weight disparities between isotopes, scientists envisioned a form of neutral ballast residing in the nucleus. A little more or less of this as yet unknown stuff would spell the difference between thorium, say, at atomic weight 232, and its isotope radiothorium, at 228.

In the new light of isotopes, Marie could see why her 1902 and 1907 figures for radium’s atomic weight did not quite match. The tiny discrepancy indicated no lack of technique on her part, no lapse in skill, but merely a different assortment of isotopes each time. Since radium now shared its place on the periodic table with several chemical twins, such as mesothorium 1 and thorium X, the atomic weight of radium in any given trial must represent an average or a median between the heaviest and lightest isotopes in the mix.[1]

Marie had played no active part in the recent discoveries about atomic structure and the nature of isotopes. Yet, in a sense, she had enabled them all. She was the one who had pursued Becquerel’s uranic rays, found them in new places, given them a new name, and recognized radioactivity as an atomic property of certain elements. Suspecting the presence of polonium and radium in pitchblende, she had pried them from rock dust by the force of her will. Everything she had done to secure radium’s place on the periodic table strengthened her own position as standard-bearer for her discovery.