Chapter Ten

SYBIL (Thorium)

MARIE HAD SERVANTS to help her at home now—a Polish governess for the girls and a housekeeper who cooked the family’s meals—but she nursed her ailing father-in-law herself. “The year 1909 is the year of the illness of Grandpère,” she wrote in a notebook, allowing the simple fact its full weight. Through the summer and early autumn, she spent as much time as she could by his side, “listening to his remembrances of passed years.” Nearness to him and caring for him might have offset, to some small degree, the distance that had separated her from her own father in his final days.

At the lab she finessed another small expansion to accommodate a few incoming researchers. An additional space in the Sorbonne Annex was now completely refitted according to her specifications. Only the sign on the door betrayed the room’s recent past as storage for “Collections Botaniques.” The new chemist from England, twenty-two-year-old May Sybil Leslie, noted the labeling mismatch and mentioned it in her first letter home.

Sybil, as she preferred to be called, had never been so far away from home. Born and raised in the Yorkshire village of Woodlesford, she became the first local girl from a working-class family to win a university scholarship. The windfall carried her to Leeds, six miles away, where she took first-class honors in chemistry at her graduation in 1908. She then completed her master’s degree and received an “Exhibition of 1851 Scholarship,” awarded only to the most exceptional young scientists and engineers. Suddenly she was free to go anywhere. She had zero experience with radioactivity, but an earnest letter of endorsement from Arthur Smithells, head of the chemistry department at the University of Leeds, eased her way into the Curie lab, her chosen destination.

Sybil Leslie found lodgings in Paris at an address that Mme. Curie suggested, then spent the first few weeks acclimating herself to the lab’s unfamiliar apparatus, such as the piezoelectric quartz, under the guidance of André Debierne.

“Monsieur Debierne, the discoverer of actinium,” Sybil reported to Professor Smithells, “is the Chef du Laboratoire and has most of the burden of the students. He is a Frenchman of the most charming type, gentle, kind, and courteous in manner, and with a vast fund of patience which he certainly needs, for the advice offered in every difficulty is ‘Demandez à M. Debierne.’” As a further testament to the man’s forbearance, Sybil noted that “he listens very patiently while I murder his language and tie myself in linguistic knots.”

M. Debierne and Mme. Curie had recently acquired several more tons of uranium ore residue, now undergoing a new separation process at the Sels du Radium factory. They hoped to isolate enough polonium for a conclusive visualization of the element’s spectrum.

“There are only two ladies besides myself,” Sybil’s letter continued, “Norwegian Mlle. Gleditsch, and French Mlle. Blanquies. Of the French lady I see very little because she does not spend all her time here, but of Mlle. Gleditsch I see much since she lives in the same pension. She has been exceedingly good to me and has prevented me from feeling lonely.”

Her orientation complete, Sybil received a specimen of the mineral thorite, a primary source of thorium, and was asked to discern what other radioelements, if any, the rock might contain. Stationed at one of the new white-tiled lab benches in the added-on room, she performed the necessary chemical analyses with the practiced ease of past experience. But the current challenge required her to test each breakdown compound product for radioactivity. Entirely new entities, undetectable except by electrometer, might emerge at any stage in her dissolutions. Perhaps the “mother” or “daughters” of thorium would reveal themselves.

May Sybil Leslie

Howard Benson, https://newwoodlesford.xyz/

In the evenings, Sybil returned to her lodgings in the rue Berthollet along a route illuminated by Paris’s emblematic streetlamps. Even as electric lighting proliferated through the city, the old gaslights still glowed, their light intensified by the presence of thorium in their mantles. The rare metal had been put to the purpose of amplifying gaslight decades before Mme. Curie discovered its radioactivity.

“Mme. Curie spends a considerable amount of time working in the laboratory,” Sybil observed, specifically in the Salle à Chimie in the courtyard, detached from the main building. “She does not appear to come around much to the students but receives them very kindly when they seek her. She does not speak English at all, nor does she appear to understand spoken English except a few scientific terms. She speaks very quickly and to the point and is very quiet in manner but by no means languid. She has a face of great intelligence and the expression is rather worn and sad in general, but she has a most charming smile at times which quite transfigures her.”

Sybil naturally enrolled in Madame’s course on radioactivity. By the end of November 1909, after several weeks of instruction, she was still finding the lectures “by no means easy to follow.” The first two or three, she said, had drawn numerous curiosity seekers eager for a glimpse of the famous lady professor. Attendance had shrunk appreciably since then. “The increasing difficulty of the lectures,” Sybil explained, “on account of the mathematics introduced and the great speed at which Mme. Curie proceeds, has gradually weeded out the audience, and for the most part only the enthusiasts who are really interested in the subject now come.”

IN DECEMBER MARIE moved Grandpère’s bed—from the bright clutter of his room, where shelves sagged under mementos, medical texts, and the novels of Victor Hugo—into the living room. She set up a cot for herself in the dining room, where she would be sure to hear him should he call out to her during the night.

At this same dark time, she saw the first glimmer of her grand new laboratory. Officials at the Sorbonne contracted with doctors at the Institut Pasteur to plan a comprehensive center for radioactivity research. One half would be devoted to the medical uses of radium, the other half to the physics and chemistry of radioelements. Marie would direct this arm of the enterprise, which was to occupy its own separate, several-story building, and be known as le Pavillon Curie.

The skin lesions reported early on by the Curies and Becquerel had piqued the interest of the medical community, and that interest had grown along with radium’s fame. In 1904 Dr. Antoine Béclère, one of the first physicians to perceive radium’s promise for medicine as a destroyer of cancerous growths, brought two long-suffering women into the Curie lab and treated their recurrent breast cancers by direct exposure to the element. By 1909 radiation therapy, also known as “curietherapy,” was administered in the hospital, via small glass ampoules of radium emanation laid on the skin surface. In the case of deep tumors, the tiny tubes or needles of radioactive gas could be surgically implanted.

The half-value of radium emanation, now a crucial constraint in medicine as well as a fundamental parameter in physics, had been measured repeatedly over the years. Pierre had determined 3.99 days as the time required for any quantity of the material to diminish by half. Ernest Rutherford later shortened that figure to 3.71 days, and recently researchers in America and Europe had recorded intermediate values of 3.88, 3.86, and 3.75. Marie considered all the factors that might have driven the various results up or down, such as the volume of gas each investigator had studied, the type of device used to quantify radioactivity, the temperature and humidity of the ambient air, and so on. Finding fault with several of the methodologies, she decisively reset the half-value, or “half-life,” of emanation at 3.86 days.[1]

She turned next, early in 1910, to the isolation of radium in its pure metallic state—something never seen in nature or in any laboratory. What would the element look like, forcibly stripped of its chloride or bromide companion, as naked and alone as a disembodied soul?

The year before Pierre died, Marie had accompanied him to a series of séances, where the dead were summoned to speak or otherwise reveal themselves. Such sessions were very popular at the time, and it was typical of Pierre to keep an open mind toward any novel phenomenon, even the trances of a spiritualist. As the couple sat with other participants in the semidarkness around the levitating table, vague apparitions hovered overhead. Marie had seen these things with her own eyes, but also with a sense of how easily the eye could be deceived.

The isolation process that she and Debierne adapted for separating radium from radium chloride was fraught with danger—not merely of failure, but of losing their radium along the way. They began with a pinch of salt, or rather a decigram of radium chloride, which they dissolved in solution so as to separate the elements by electrolysis: They dipped two metal strips, or electrodes, into the solution, one made of mercury, the other of platinum-iridium, and both connected to a battery. Current flowing between the electrodes invited the radium ions to collect on—and combine with—the mercury electrode.

They then sealed the radium-mercury amalgam in an iron capsule, which they heated, very gradually, to boil off the mercury. At 700 degrees, when they feared the radium itself might vaporize, they halted the procedure.

Having at last trapped their quarry, they saw the unalloyed metallic radium shining with a brilliant whiteness. It adhered so tightly to the iron capsule that they had to pry it out with a chisel-tipped tool. A fragment that fell on a sheet of paper burned right through, leaving a black-rimmed hole. Exposed to air, the bright radium darkened in combination with nitrogen. It reacted violently with water, forming an oxide and a blackish residue. When assessed for radioactivity, it behaved as radium always behaved, releasing alpha particles and radium emanation at a rate as regular and recognizable as a heartbeat.

Ever-practical Marie would not consider preserving the pure radium in this bizarre state, when every shred was needed for other purposes. A unicorn could not do the work of a horse. She and Debierne set about turning their hard-won sample back into a tiny pillar of salt.

THE TYPICAL RAIN and chill of the Paris winter grew into a deluge in late January 1910, when the Seine overflowed its banks and flooded some fourteen thousand buildings throughout the city. The main thoroughfares turned into river tributaries. A metre of water covered the tracks at the Gare d’Orsay terminal. Resilient Parisians made the best of things at first, navigating the inundated streets in boats or on the raised wooden walkways hastily built to meet the emergency. After several weeks, however, with no relief in sight, hordes of residents evacuated.

The pension where Ellen Gleditsch and Sybil Leslie lived stayed dry, but flooding at the Sorbonne Annex cut off the Curie lab’s heat and electricity. Sybil described the scene to Smithells—how only a few of the rooms could be lighted by gas jets, leaving unlit areas to be passed through “candle in hand.” The cold made it difficult to remain any length of time on task, and dampness rendered the electroscopes useless. The one Sybil used, she quipped, had become “a veritable hygrometer” (an instrument for measuring the content of water vapor in the atmosphere).

The Curie home in Sceaux lay well beyond the flood zone. Dr. Eugène Curie died peacefully there on February 25. When the family gathered at the local cemetery, Marie prevailed on the gravediggers to bring up Pierre’s coffin before burying Grandpère. She wanted the beloved patriarch to be interred nearer to his wife and, by the same switch, to reserve the space just above Pierre for herself.

Irène, who had not witnessed her father’s original burial, slumped under the weight of both losses. “She is very shaken,” Marie wrote in her journal. “Her sadness is profound … She suffers and matures.” Irène’s maturity was further hastened by her classmates at the collège she now attended in Paris, where her intellectual ability had placed her among students beyond her twelve years. Ève, age five, was enrolled at an elementary school, while also receiving private tutorials from her mother, first thing each morning, and continuing her music lessons.

In March, when the floodwaters receded, Sybil Leslie professed herself astonished to see how rapidly Paris could shrug off its sorrows and “reassume its smiles.” With light, heat, and dry equipment, she continued dividing and subdividing her fifty grams of thorite until she arrived at a few tantalizing active traces. These, unfortunately, were too scanty to identify. There was nothing for it but to start over, this time with much, much more material. “After working with grams in beakers & evaporating dishes,” she noted, “it is rather difficult to adjust oneself to kilograms in huge jars & earthenware bowls.”

In spite of these difficulties, Sybil remained confident and focused on her experiments. Her letters to Smithells bore none of the insecurity or self-doubt that Harriet Brooks had often expressed to Rutherford. In the three years since leaving the Curie lab, Harriet had convinced herself that women in general were ill-suited to scientific research. She aired this belief before the McGill Alumnae Society in April 1910, when its executive committee invited Mrs. Frank Pitcher to speak about her experience of working under Mme. Curie.

“Perhaps it was a feeling of delicacy that prompted the committee to confine my attention to Mme. Curie this p.m., that I might not be forced to expose the poverty of women’s contributions to physical science.” Harriet did not rue the lack of opportunities for women, but rather blamed the dearth of women scientists on certain shortcomings of her sex. “The combination of the ability to think in mathematical formulas and to manipulate skillfully the whimsical instruments of a physical laboratory—a combination necessary to attain eminence in physics—is apparently one seldom met with in women,” she said. She seemed to have forgotten that she herself had once embodied these abilities. Now she took pains to assure her fellow alumnae that even a very large man was far more likely than the average woman to master the delicate and intricate tasks of laboratory science. “It is no rare thing to see a man with hands twice the size of one’s own and every appearance of being very dangerous to fragile furniture”—this was Rutherford to a T—“who will handle quartz fibers, so fine that they can be seen only against a black cloth, with the same ease with which we would disentangle a skein of wool.”

Even if gifted with greater “deftness of hand,” Harriet thought women would still feel indifferent toward the physical sciences due to “their want of human interest.” Nevertheless, she said, the science of radioactivity had seen astounding developments in which “Mme. Curie has played an important and unforgettable part.” Here she proceeded to describe such arcana as atomic weight determinations, the theory of radioactive transformation, the difference between alpha and beta radiation, and the heat release of radium.

“It is naturally difficult to separate the work of Mme. Curie from that of her husband during the years in which they worked together, but I have always had the impression that she was the pioneer in planning and he the skilled experimenter,” Harriet concluded, as though to prove her argument. “At his death his wife was appointed his successor at the Sorbonne, an honor to a woman quite without precedent at that ancient university. The duties of the position, the growth of the research laboratory under her care and no doubt also the loss of her skillful collaborator have somewhat lessened her output of work in the last few years.”

In fact, Marie had rebounded after the fallow period immediately following Pierre’s death. Actively re-engaged in research in 1910, she was also preparing her textbook on radioactivity for imminent publication, arranging for the addition of another four researchers to her lab, and playing a central role in planning the new Institut du Radium. Friends remarked on her rejuvenated appearance. One evening she startled them all by showing up at a social gathering in a white dress instead of her customary black.

Marie was experiencing a renascence of romantic feelings that she thought had died with Pierre. These centered on Paul Langevin, who had taken to confiding in her the details of his unhappy marriage. Marie and Paul had long been friends as well as colleagues at Sèvres, but now, listening to the litany of his distress aroused her sympathy and awakened her desire. Although Paul’s wife stood between them, it seemed that Pierre bound them the more tightly together through their shared memories of him in happier times.

In mid-July, after Irène and Ève left for a beach vacation in Brittany with their aunt Helena, Marie visited Paul in the two-room apartment he rented on the rue Banquier. There, as discreetly as possible, they became secret lovers.

“My dear Paul,” she wrote to him later that summer from the Brittany coast, “I spent yesterday evening and night thinking of you, of the hours that we have passed together and of which I have kept a delicious memory. I still see your good and tender eyes, your charming smile, and I think only of the moment when I will find again all the sweetness of your presence.”