Speaking of mistakes, no element has been discovered for the “first time” more times than element forty-three. It’s the Loch Ness monster of the elemental world.
In 1828, a German chemist announced the discovery of the new elements “polinium” and “pluranium,” one of which he presumed was element forty-three. Both turned out to be impure iridium. In 1846, another German discovered “ilmenium,” which was actually niobium. The next year someone else discovered “pelopium,” which was niobium, too. Element forty-three disciples at last got some good news in 1869, when Mendeleev constructed his periodic table and left a tantalizing gap between forty-two and forty-four. However, though good science itself, Mendeleev’s work encouraged a lot of bad science, since it convinced people to look for something they were predisposed to find. Sure enough, eight years later one of Mendeleev’s fellow Russians inked “davyium” into box forty-three on the table, even though it weighed 50 percent more than it should have and was later determined to be a mix of three elements. Finally, in 1896 “lucium” was discovered—and discarded as yttrium—just in time for the twentieth century.
The new century proved even crueler. In 1909, Masataka Ogawa discovered “nipponium,” which he named for his homeland (Nippon in Japanese). All the previous faux forty-threes had been contaminated samples or previously discovered trace elements. Ogawa had actually discovered a new element—just not what he claimed. In his rush to seize element forty-three, he ignored other gaps in the table, and when no one could confirm his work, he retracted it, ashamed. Only in 2004 did a countryman reexamine Ogawa’s data and determine he had isolated element seventy-five, rhenium, also undiscovered at the time, without knowing it. It depends whether you’re a half-full or half-empty kind of person if you think Ogawa would be posthumously pleased to find out he’d discovered at least something, or even more vexed at his wrenching mistake.
Element seventy-five was discovered unambiguously in 1925 by three more German chemists, Otto Berg and the husband and wife team of Walter and Ida Noddack. They named it rhenium after the Rhine River. Simultaneously, they announced yet another stab at element forty-three, which they called “masurium” after a region of Prussia. Given that nationalism had destroyed Europe a decade earlier, other scientists did not look kindly on those Teutonic, even jingoistic names—both the Rhine and Masuria had been sites of German victories in World War I. A continent-wide plot rose up to discredit the Germans. The rhenium data looked solid, so scientists concentrated on the sketchier “masurium” work. According to some modern scholars, the Germans might have discovered element forty-three, but the trio’s paper contained sloppy mistakes, such as overestimating by many thousands of times the amount of “masurium” they had isolated. As a result, scientists already suspicious of yet another claim for element forty-three declared the finding invalid.
Only in 1937 did two Italians isolate the element. To do so, Emilio Segrè and Carlo Perrier took advantage of new work in nuclear physics. Element forty-three had proved so elusive until then because virtually every atom of it in the earth’s crust had disintegrated radioactively into molybdenum, element forty-two, millions of years ago. So instead of sifting through tons of ore like suckers for a few micro-ounces of it (as Berg and the Noddacks had), the Italians had an unknowing American colleague make some.
A few years earlier that American, Ernest Lawrence (who once called Berg and the Noddacks’ claim for element forty-three “delusional”), had invented an atom smasher called a cyclotron to mass-produce radioactive elements. Lawrence was more interested in creating isotopes of existing elements than in creating new ones, but when Segrè happened to visit Lawrence’s lab on a tour of America in 1937, Segrè heard that the cyclotron used replaceable molybdenum parts—at which point his internal Geiger counter went wild. He cagily asked to look at some discarded scraps. Weeks later, at Segrè’s request, Lawrence happily flew a few worn-out molybdenum strips to Italy in an envelope. Segrè’s hunch proved correct: on the strips, he and Perrier found traces of element forty-three. They had filled the periodic table’s most frustrating gap.
Naturally, the German chemists did not abandon their claims for “masurium.” Walter Noddack even visited and quarreled with Segrè in the Italian’s office—and did so dressed in an intimidating, quasi-military uniform covered with swastikas. This didn’t endear him to the short, volatile Segrè, who also faced political pressure on another matter. Officials at the University of Palermo, where Segrè worked, were pushing him to name his new element “panormium,” after the Latin for Palermo. Perhaps wary because of the nationalistic debacle over “masurium,” Segrè and Perrier chose technetium, Greek for “artificial,” instead. It was fitting, if dull, since technetium was the first man-made element. But the name cannot have made Segrè popular, and in 1938 he arranged for a sabbatical abroad at Berkeley, under Lawrence.
There’s no evidence Lawrence held a grudge against Segrè for his molybdenum gambit, but it was Lawrence who lowballed Segrè later that year. In fact, Lawrence blurted out, oblivious to the Italian’s feelings, how happy he was to save $184 per month to spend on equipment, like his precious cyclotron. Ouch. This was further proof that Lawrence, for all his skill in securing funds and directing research, was obtuse with people. As often as Lawrence recruited one brilliant scientist, his dictatorial style drove another away. Even a booster of his, Glenn Seaborg, once said that Lawrence’s world-renowned and much-envied Rad Lab—and not the Europeans who did—should have discovered artificial radioactivity and nuclear fission, the most momentous discoveries in science at the time. To miss both, Seaborg rued, was “scandalous failure.”
Still, Segrè might have sympathized with Lawrence on that last account. Segrè had been a top assistant to the legendary Italian physicist Enrico Fermi in 1934 when Fermi reported to the world (wrongly, it turned out) that by bombarding uranium samples with neutrons, he had “discovered” element ninety-three and other transuranic elements. Fermi long had a reputation as the quickest wit in science, but in this case his snap judgment misled him. In fact, he missed a far more consequential discovery than transuranics: he had actually induced uranium fission years before anyone else and hadn’t realized it. When two German scientists contradicted Fermi’s results in 1939, Fermi’s whole lab was stunned—he had already won a Nobel Prize for this. Segrè felt especially chagrined. His team had been in charge of analyzing and identifying the new elements. Worse, he instantly remembered that he (among others) had read a paper on the possibility of fission in 1934 and had dismissed it as ill conceived and unfounded—a paper by, of all the damned luck, Ida Noddack.*
Segrè—who later became a noted science historian (as well as, incidentally, a noted hunter of wild mushrooms)—wrote about the fission mistake in two books, saying the same terse thing both times: “Fission… escaped us, although it was called specifically to our attention by Ida Noddack, who sent us an article in which she clearly indicated the possibility…. The reason for our blindness is not clear.”* (As a historical curiosity, he might also have pointed out that the two people who came closest to discovering fission, Noddack and Irène Joliot-Curie—daughter of Marie Curie—and the person who eventually did discover it, Lise Meitner, were all women.)
Unfortunately, Segrè learned his lesson about the absence of transuranic elements too literally, and he soon had his own solo scandalous failure to account for. Around 1940, scientists assumed that the elements just before and just after uranium were transition metals. According to their arithmetic, element ninety fell in column four, and the first non–naturally occurring element, ninety-three, fell in column seven beneath technetium. But as the modern table shows, the elements near uranium are not transition metals. They sit beneath the rare earths at the bottom of the table and act like rare earths, not like technetium, in chemical reactions. The reason for chemists’ blindness back then is clear. Despite their homage to the periodic table, they didn’t take periodicity seriously enough. They thought the rare earths were
strange exceptions whose quirky, clingy chemistry would never repeat. But it does repeat: uranium and others bury electrons in f-shells just like the rare earths. They must, therefore, jump off the main periodic table at the same point and behave like them in reactions. Simple, at least in retrospect. A year after the bombshell discovery of fission, a colleague down the hall from Segrè decided to try again to find element ninety-three, so he irradiated some uranium in the cyclotron. Believing (for the reasons above) that this new element would act like technetium, he asked Segrè for help, since Segrè had discovered technetium and knew its chemistry better than anyone. Segrè, an eager element hunter, tested the samples. Taking after his quick-witted mentor, Fermi, he announced that they acted like rare earths, not like heavy cousins of technetium. More humdrum nuclear fission, Segrè declared, and he dashed off a paper with the glum title “An Unsuccessful Search for Transuranic Elements.”
But while Segrè moved on, the colleague, Edwin McMillan, felt troubled. All elements have unique radioactive signatures, and Segrè’s “rare earths” had different signatures than the other rare earths, which didn’t make sense. After careful reasoning, McMillan realized that perhaps the samples acted like rare earths because they were chemical cousins of rare earths and diverged from the main periodic table, too. So he and a partner redid the irradiation and chemical tests, cutting Segrè out, and they immediately discovered nature’s first forbidden element, neptunium. The irony is too good not to point out. Under Fermi, Segrè had misidentified nuclear fission products as transuranics. “Apparently not learning from that experience,” Glenn Seaborg recalled, “once again Segrè saw no need to follow up with careful chemistry.” In the exact opposite blunder, Segrè sloppily misidentified transuranic neptunium as a fission product.
Though no doubt furious with himself as a scientist, perhaps as a science historian Segrè could appreciate what happened next. McMillan won the Nobel Prize in Chemistry in 1951 for this work. But the Swedish Academy had rewarded Fermi for discovering the transuranic elements; so rather than admit a mistake, it defiantly rewarded McMillan only for investigating “the chemistry of the transuranium elements” (emphasis added). Then again, since careful, mistake-free chemistry had led him to the truth, maybe that wasn’t a slight.
* * *
If Segrè proved too cocksure for his own good, he was nothing compared to the genius just down I-5 in southern California, Linus Pauling.
After earning his Ph.D. in 1925, Pauling had accepted an eighteen-month fellowship in Germany, then the center of the scientific universe. (Just as all scientists communicate in English today, back then it was de rigueur to speak German.) But what Pauling, still in his twenties, learned about quantum mechanics in Europe soon propelled U.S. chemistry past German chemistry and himself onto the cover of Time magazine.
In short, Pauling figured out how quantum mechanics governs the chemical bonds between atoms: bond strength, bond length, bond angle, nearly everything. He was the Leonardo of chemistry—the one who, as Leonardo did in drawing humans, got the anatomical details right for the first time. And since chemistry is basically the study of atoms forming and breaking bonds, Pauling single-handedly modernized the sleepy field. He absolutely deserved one of the great scientific compliments ever paid, when a colleague said Pauling proved “that chemistry could be understood rather than being memorized” (emphasis added).
After that triumph, Pauling continued to play with basic chemistry. He soon figured out why snowflakes are six-sided: because of the hexagonal structure of ice. At the same time, Pauling was clearly itching to move beyond straightforward physical chemistry. One of his projects, for instance, determined why sickle-cell anemia kills people: the misshaped hemoglobin in their red blood cells cannot hold on to oxygen. This work on hemoglobin stands out as the first time anyone had traced a disease to a malfunctioning molecule,* and it transformed how doctors thought of medicine. Pauling then, in 1948, while laid up with the flu, decided to revolutionize molecular biology by showing how proteins can form long cylinders called alpha-helixes. Protein function depends largely on protein shape, and Pauling was the first to figure out how the individual bits in proteins “know” what their proper shape is.
In all these cases, Pauling’s real interest (besides the obvious benefits to medicine) was in how new properties emerge, almost miraculously, when small, dumb atoms self-assemble into larger structures. The really fascinating angle is that the parts often betray no hint of the whole. Just as you could never guess, unless you’d seen it, that individual carbon, oxygen, and nitrogen atoms could run together into something as useful as an amino acid, you’d have no idea that a few amino acids could fold themselves into all the proteins that run a living being. This work, the study of atomic ecosystems, was a step up in sophistication even from creating new elements. But that jump in sophistication also left more room for misinterpretation and mistakes. In the long run, Pauling’s easy success with alpha-helixes proved ironic: had he not blundered with another helical molecule, DNA, he would surely be considered one of the top five scientists ever.
Like most others, Pauling was not interested in DNA until 1952, even though Swiss biologist Friedrich Miescher had discovered DNA in 1869. Miescher did so by pouring alcohol and the stomach juice of pigs onto pus-soaked bandages (which local hospitals gladly gave to him) until only a sticky, goopy, grayish substance remained. Upon testing it, Miescher immediately and self-servingly declared that deoxyribonucleic acid would prove important in biology. Unfortunately, chemical analysis showed high levels of phosphorus in it. Back then, proteins were considered the only interesting part of biochemistry, and since proteins contain zero phosphorus, DNA was judged a vestige, a molecular appendix.*
Only a dramatic experiment with viruses in 1952 reversed that prejudice. Viruses hijack cells by clamping onto them and then, like inverse mosquitoes, injecting rogue genetic information. But no one knew whether DNA or proteins carried that information. So two geneticists used radioactive tracers to tag both the phosphorus in viruses’ phosphorus-rich DNA and the sulfur in their sulfur-rich proteins. When the scientists examined a few hijacked cells, they found that radioactive phosphorus had been injected and passed on but the sulfurous proteins had not. Proteins couldn’t be the carriers of genetic information. DNA was.*
But what was DNA? Scientists knew a little. It came in long strands, and each strand consisted of a phosphorus-sugar backbone. There were also nucleic acids, which stuck out from the backbone like knobs on a spine. But the shape of the strands and how they linked up were mysteries—important mysteries. As Pauling showed with hemoglobin and alpha-helixes, shape relates intimately to how molecules work. Soon DNA shape became the consuming question of molecular biology.
And Pauling, like many others, assumed he was the only one smart enough to answer it. This wasn’t, or at least wasn’t only, arrogance: Pauling had simply never been beaten before. So in 1952, with a pencil, a slide rule, and sketchy secondhand data, Pauling sat down at his desk in California to crack DNA. He first decided, incorrectly, that the bulky nucleic acids sat on the outside of each strand. Otherwise, he couldn’t see how the molecule fit together. He accordingly rotated the phosphorus-sugar backbone toward the molecule’s core. Pauling also reasoned, using the bad data, that DNA was a triple helix. That’s because the bad data was taken from desiccated, dead DNA, which coils up differently than wet, live DNA. The strange coiling made the molecule seem more twisted than it is, bound around itself three times. But on paper, this all seemed plausible.
Everything was humming along nicely until Pauling requested that a graduate student check his calculations. The student did and was soon tying himself in knots trying to see where he was wrong and Pauling was right. Eventually, he pointed out to Pauling that it just didn’t seem like the phosphate molecules fit, for an elementary reason. Despite the emphasis in chemistry classes on neutral atoms, sophisticated chemists don’t think of elements that way. In nature, especially in biology, many elem
ents exist only as ions, charged atoms. Indeed, according to laws Pauling had helped work out, the phosphorus atoms in DNA would always have a negative charge and would therefore repel each other. He couldn’t pack three phosphate strands into DNA’s core without blowing the damn thing apart.
The graduate student explained this, and Pauling, being Pauling, politely ignored him. It’s not clear why Pauling bothered to have someone check him if he wasn’t going to listen, but Pauling’s reason for ignoring the student is clear. He wanted scientific priority—he wanted every other DNA idea to be considered a knockoff of his. So contra his usual meticulousness, he assumed the anatomical details of the molecule would work themselves out, and he rushed his phosphorus-in, triple-stranded model into print in early 1953.
Meanwhile, across the Atlantic, two gawky graduate students at Cambridge University pored over advance copies of Pauling’s paper. Linus Pauling’s son, Peter, worked in the same lab as James Watson and Francis Crick* and had provided the paper as a courtesy. The unknown students desperately wanted to solve DNA to make their careers. And what they read in Pauling’s paper flabbergasted them: they had built the same model a year before—and had dismissed it, embarrassed, when a colleague had shown what a shoddy piece of work their triple helix was.
During that dressing-down, however, the colleague, Rosalind Franklin, had betrayed a secret. Franklin specialized in X-ray crystallography, which shows the shapes of molecules. Earlier that year, she had examined wet DNA from squid sperm and calculated that DNA was double-stranded. Pauling, while studying in Germany, had studied crystallography, too, and probably would have solved DNA instantly if he’d seen Franklin’s good data. (His data for dried-out DNA was also from X-ray crystallography.) However, as an outspoken liberal, Pauling had had his passport revoked by McCarthyites in the U.S. State Department, and he couldn’t travel to England in 1952 for an important conference, where he might have heard of Franklin’s work. And unlike Franklin, Watson and Crick never shared data with rivals. Instead, they took Franklin’s abuse, swallowed their pride, and started working with her ideas. Not long afterward, Watson and Crick saw all their earlier errors reproduced in Pauling’s paper.
Sam Kean Page 13
