The life and science of Harold C. Urey.
Chicago: University of Chicago Press, 2019.
cloth, 248 pp., ISBN 978–0–226–66208–4, $US27.50.
University of Chicago Press: https://press.uchicago.edu/
I beg my readers to excuse this ‘shaggy dog’ story, disguised as a book review.
When did I first encounter Harold Urey?
Oh, I had to cut class to do it. It was a total accident, serendipity at its finest. Or as Louis Pasteur remarked “Dans les domaines de l'observation, le hasard ne favorise que l’esprit préparé” (or “In the fields of observation chance favors only the prepared mind”) .
During the course of a regular school year, there was never enough time to do proper research on a science project. I opted for the simplest solution, by avoiding classes for a day or two or even more to work on research and especially on my project’s paper in a real library, not a mere mortal school or public library. I must have been the only high school student in history to dodge classes to routinely visit a library. Of course, my fellow conspirator in this strategy was my father, who dutifully wrote excuses repeatedly for my absences, thinking that I was completely daft to miss school to study arcane, dusty journals and books. Nevertheless, he supported my oddity in this regard, making up quite reasonable excuses to my teachers and the school administration for my disappearances.
Given that the theme of my high school research was paleontology, the nearest library with the finest facilities in that subject area was the Library of the Field Museum. The Curator of Invertebrate Paleontology, Dr. Eugene Richardson, had introduced me to one of the Museum’s librarians, Peyton Fawcett, in the summer of 1966, so I was a known quantity to certain occupants on the northwest corner of the third floor of the Museum.
In the winter months of January and February 1967, I was madly completely my project on the evolution of certain species of a common Cretaceous oyster called Exogyra . I had collected sacks of them along road cuts in northeastern Mississippi in the past summer. I had suspicions about how the various species changed over time, in part aided by some basic measurements of their physical attributes and statistical analysis, stimulated largely by Dr. Richardson’s copy of Simpson and Roe’s Quantitative Zoology . I also found by chance in the Museum library in the card catalog John Imbrie’s magnificent paper entitled “Biometrical methods in the study of invertebrate fossils” , which greatly helped me develop a quantitative approach to speciation in Exogyra.
In those days before inexpensive photocopying or PDFs, I hysterically took notes in longhand, filling page after page of my notebook with excerpts from papers and books collected by library staff from the restricted, closed stacks, along with my thoughts and ideas on what I was inhaling from each printed page. No lunch or even coffee breaks for me.
Late that chilly afternoon, I decided to walk west along a hallway just south of the library’s reading room to the closest bathroom. That same path was a few steps from Dr. Richardson’s office, and I just wanted to thank him once again for his help and advice.
Next to Dr. Richardson’s office, there was a small room filled with offprints on geology and paleontology. Enter serendipity. For whatever reason, I walked into the room and looked at a desk on its west edge, where tall windows allowed a little light through a gray overcast sky. A wooden tray contained offprints awaiting filing into folders and boxes by an elderly volunteer. On the top of the pile was a small offprint, in brown paper wrappers. It was entitled “Measurement of paleotemperatures and temperatures of the Upper Cretaceous of England, Denmark, and the southeastern United States.” The authors of this paper, published in April 1951, were listed on the cover as “H.C. Urey, H.A. Lowenstam, S. Epstein, and C.R. McKinney.” 
|Figure 1: My first encounter with Harold Urey in print, in his “Measurement of paleotemperatures and temperatures of the Upper Cretaceous of England, Denmark, and the southeastern United States“ (1951).|
It was my very first encounter with Harold Clayton Urey. I sat down and read, re-read, and re-re-read the document that winter afternoon. It was my introduction to Nobel Laureate Urey, and it was not my last.
Dr. Urey’s association with Heinz Lowenstam as a co-author markedly raised his reputation in my eyes, since Harold Urey was a complete unknown to me on that day early in 1967. I had read everything by Heinz Lowenstam on the Silurian reefs in the Chicago area, since those reefs — especially the massive reef exposed west of Thornton, Illinois — were my favorite local fossil hunting grounds. Dr. Lowenstam’s Silurian papers helped me visualize life some 410 million years ago, allowing me to swim, albeit in my imagination, in shallow reef waters with trilobites, crinoids, cephalopods, brachiopods, coral, and other invertebrates.
I walked next door to Dr. Richardson’s office and asked him point blank if I could borrow the Urey, et al. paper for a few weeks to study it in more detail. The changing temperatures of an epicontinental sea could help explain speciation since oysters were sensitive to environmental warming and cooling. Dr. Richardson agreed that I could examine the paper for a little longer. He also recommended that I look for more research by Dr. Urey’s team at the University of Chicago on fossils and isotopes.
So began a long intellectual journey for me, inspired in large part by meeting Harold Urey, in print, over half a century ago.
A few years later, in the summer of 1969, I was fortunate to work in Harold Urey’s former laboratory at the University of Chicago’s Fermi Institute for Nuclear Studies, examining stable isotopes in Cretaceous fossil mollusks, just as Harold Urey, Heinz Lowenstam, and others had done in the late 1940s and early 1950s . I was born in 1950 just a few blocks away from Urey’s lab at the University of Chicago’s Lying-In Hospital. The laboratory in that summer was a little different from Urey’s time, preparing for the arrival of lunar samples in September. I had a small window of time to perform a number of experiments. During the day, I was sequestered in the fossil collections at the Field Museum as a Shinner Fellow for the summer assigned to Dr. Richardson, identifying and organizing invertebrate fossils. In evenings and weekends, I operated a mass spectrometer, collecting isotopic values on samples from Cretaceous mollusks. Sleep was vastly overrated that summer.
In the lab, I poured over laboratory notebooks from the fossil experiments with Urey, Lowenstam, Epstein, and others, careful not to upset the glass preparatory lines or the mass spectrometer. Toshiko Mayeda, the institutional memory of those Urey days, helped me as much as possible. Over the years, I eventually met other members of the lab from that important period when stable isotopic geochemistry was born, such as Heinz Lowenstam, Samuel Epstein, Cesare Emiliani, and Harmon Craig. Alas, I never met in person the individual who started me on this intellectual journey, Harold Urey.
As you might expect, I was quite looking forward to studying Matthew Shindell’s The life and science of Harold C. Urey, especially reading descriptions of my hero and detailed explanations of his varied discoveries and accomplishments. I had read decades earlier the first printed Urey biography — Harold Urey; the man who explored from earth to moon, by Alvin and Virginia Silverstein . The Silverstein biography was aimed at younger readers, so a true, deeper, comprehensive explanation of Urey’s life and work was long overdue.
I guess that I will have to wait a little longer for that great biography of Urey, with proper explanations of Urey’s science, his efforts as a tireless experimenter as well as his humanity.
At a macroscopic level, there is little explanation in Shindell for a lay audience of some of Urey’s most significant accomplishments. For example, I was looking in Shindell’s biography for behind-the-scene descriptions of the work leading to the monumental lecture for the 1946 Liversidge Award of the Royal Society of Chemistry. In my opinion, Urey’s lecture resulted in one of his most significant papers, entitled “The thermodynamic properties of isotopic substances” . This paper led to the birth of an entire discipline in geochemistry, the examination of stable isotopic variations in natural and extraterrestrial materials. Much of our current knowledge about the chemistry of the Earth and the solar system has been provided by thousands of experiments measuring stable isotopes in a wide variety of materials.
|Figure 2: Harold Urey's paper “The thermodynamic properties of isotopic substances” from the Journal of the Royal Society of Chemistry (1947).|
In Shindell’s text, the actual Liversidge Lecture is summarized all too quickly , without explaining in any detail the magnificent importance of understanding something seemingly abstract as the vibrational differences of different isotopes. Urey explained it perfectly in a 1948 paper in Science [:
|“The energy and entropy and hence the free energy of chemical substances depend on the vibration frequencies of the molecules, and these depend on the masses of the atoms. Without going into the details of the mathematical calculations, we may say that the observed differences agree exactly with calculations where these are possible. If calcium carbonate is crystallized slowly in the presence of water at 0° C, the calculations show that the ratio of the oxygen isotopes in the calcium carbonate should be 1.026 to 500 if the ratio of the isotopes in the water is 1 to 500, i.e., oxygen 18 is very slightly concentrated in the calcium carbonate in relation to the water. On the other hand, if the temperature is 25° C, the oxygen isotopes will be concentrated only to the extent of 1.022 as compared with 1 in 500 in water. This shows that there is a slight temperature coefficient for the abundance of 018 isotope in the calcium carbonate as compared with that in the water. In fact, the amount of this fractionation is so slight that the atomic weight of oxygen in the calcium carbonate will be changed by only 0.0000007 atomic weight units as the temperature is changed by 1° C. A change in temperature from 0° to 25° will change the atomic weight of the oxygen by only 0.00002 atomic weight units.“|
Shindell notes that Urey’s calculations were based on a “more sophisticated method developed for the SAM Lab by Jacob Bigeleisen and Maria Goeppert Mayer.” [ Let’s unbundle that little phrase.
The method in question involved quantum mechanical calculations that examine equilibrium fractionation of stable isotopes, dependent on vibrational states of atoms and molecules. What does mean? Atoms in molecules dance in specific ways, vibrating and rotating with certain kinds of bond energies (the amount of energy required to break those bonds holding atoms together in molecules). Heavier atoms with isotopes in molecules have greater bond energies. Quantum mechanics makes it possible to calculate the strength of these bonds. In turn these vibrational differences affect chemical reactions, in what are called exchange reactions. For these reactions, equilibrium constants can be calculated. Harold Urey found, by these calculations, that there are effects caused by temperature. For the reaction between water and calcium carbonate, there is a preference in carbonate to accumulate heavier isotopes of oxygen. Dr. Urey realized that he had discovered a time machine, a way to measure temperatures in the geological past. Of course, there were many factors that could confound the operation of this chemical-mechanical time machine. Nevertheless, over the past 70 years, this device has worked better than any H.G. Wells’ contraption in sampling the conditions of long-lost seas, thousands of times.
Ok, so let’s say that off-the-top-of-the-head description explains the “sophisticated method.”
What’s the “SAM Lab”?
First it should be called the SAM Labs [, since multiple sites at Columbia University were used. During World War II, at Columbia, a group was set up to investigate the separation of uranium isotopes in order to develop a nuclear weapon. Uranium-235 (235U) is necessary to create a critical reaction, but is scarce in ordinary uranium, accounting for 0.7 percent. More abundant is uranium-238 (238U) at 99.2 percent. 238U absorbs neutrons from 235U. Hence, natural critical reactions are scarce thanks to 238U [. Essentially, the SAM Labs were established to develop efficient ways to separate 235U. SAM is a typical Manhattan project acronym, meaning Substitute Alloy Materials (SAM).
Maria Goeppert Mayer was recruited by Harold Urey to become a critical part of the SAM Labs, because of her quantum mechanical skills, calculational verve, and sheer quick-wittedness. Urey knew Goeppert Mayer from Johns Hopkins University, as Shindell mentions [ — yet Shindell does not make it obvious to the reader that Urey brought Goeppert Mayer to Columbia’s SAM Labs because of his experiences professionally earlier with Goeppert Mayer.
Goeppert Mayer published with Bigeleisen a fundamental paper in May 1947 in the Journal of Chemical Physics on equilibrium constants. Entitled “Calculation of equilibrium constants for isotopic exchange reactions”, this document provided important information that demonstrated that the chemical separation of isotopes was a quantum effect [. I can only assume that Shindell is referring to this 1947 paper in his phrase “more sophisticated method developed for the SAM Lab by Jacob Bigeleisen and Maria Goeppert Mayer.” Yet there is other evidence that it was Maria Goeppert Mayer and Edward Teller that created the proper methods in 1943 at the Substitute Alloy Materials Laboratories at Columbia University. Yes, that Edward Teller.
|Figure 3: Edward Teller and Maria Goeppert Mayer.|
Note: Photograph by Francis Simon, courtesy American Institute of Physics, Emilio Segrè Visual Archives, at https://photos.aip.org/history-programs/niels-bohr-library/photos.
Edward Teller stated that [:
|“Maria Mayer returned [after recuperation from a gall bladder operation] to work on a Monday in December 1943. She came to see me and asked how far along I was with the final report [on photochemical isotope separation]. I told her that I was not working on it. She asked me what I was doing. I showed her the progress I had made on an alternative ... method of calculating isotopic partition function ratios, which could be used to calculate chemical exchange enrichment factors. After listening to my approach ... she said it was interesting and would I mind if she joined me in this project. I was new to this field and was delighted that she found my work sufficiently interesting to work on it with me. Her next sentence was a suggestion which completed the formulation of the concept of an isotopic reduced partition function ratio that revolutionized the field of isotopic chemistry. Ultimately it has opened up the new field of isotopic geology and led to major applications in biology and chemistry and practical applications in isotopic separation processes.“ [My emphasis]|
So, instead of writing “more sophisticated method developed for the SAM Lab [sic] by Jacob Bigeleisen and Maria Goeppert Mayer”, more correctly it should read “more sophisticated method developed at the SAM Laboratories at Columbia University by Edward Teller and Maria Goeppert Mayer in 1943.” Then, it would have been grand in Shindell’s text to have some sort of explanation of what the “method” meant in understanding the dance (vibrations, rotations) of molecules with different stable isotopes. I am sure that then we would have heard the sudden crash of many scales falling from readers’ eyes in understanding the real significance of Harold Urey’s insights into the utility of stable isotopes.
There are other occasions where Shindell fails to connect the dots for readers. I certainly blame him in part, as well as his editors and readers at the Press, for not catching at least some of these inconsistencies, even failures, to follow evidence in plain, printed sight in the literature and in archival documents.
Shindell misses the boat in humanizing Urey, too. Some evidence on this side of Urey appears in oral histories and interviews with individuals who worked in his lab at the Institute for Nuclear Studies on South Ellis Avenue at the University of Chicago. For example, Heinz Lowenstam was a key part of the group deciphering temperatures of ancient oceans with Urey’s time machine in the late 1940s and early 1950s. He described collecting fossils with Urey [:
“He [Urey] came along with me on my first big field trip to Tennessee, and clear down to Florida and Alabama, and the East Coast. We came to Philadelphia, to that area, collecting fossils. I’ll never forget him at the first outcrop. He was like a kid with a little new toy. ‘Come over here, come over here! Look at this fossil! What is it? What does it mean?’ It was such a pleasure to see an older man being so enthusiastic. I had to restrain him at the beginning, because otherwise I couldn’t get much done. He just was all over the place. When we came to the Pee Dee River in South Carolina, where we saw an outcrop of some extinct cuttlefish concentrations, he was ready to grab. I said, ‘No, Harold. We first take a picture. We number and label each specimen. Because how else do we tell how that deposit’s been laid down over several million years?’ By that time I had him in the harness. He helped me, and we worked as equals doing that. We come back to Chicago, run the oxygen isotopes, and find out they are all the same temperature. They were all from the same geologic period. But it could have been very exciting if it had been different. So I learned a lot from him.
On that trip, I finally said to him, ‘Tell me one thing. Why did you not follow Niggli and go into petrology, determine temperatures of minerals? Why fossils?’ He had insisted that the first thing we’d study was the end of the Cretaceous — the time of the end of the dinosaurs — and I was curious about that, too. He said, ‘I’ll tell you a little secret. I used to teach biology when I was a young man in Montana. I read all about dinosaurs, and got all excited about it. I always wanted to know why they died out. Maybe there was a climatic change — a chilling or something.’ So that decided him. While he was wrong about why the dinosaurs died out, he published later, in ’73, a paper where he said that at each major boundary in the geologic column there was evidence of an asteroid or meteorite [impact] effect [. That early, he was thinking along the same lines we are now. He wasn’t so far off with the temperature either. The latest date I showed, there was first a low and then a high spike. So he was really in the right ballpark.”
I am well acquainted with at least one of those fossil locales noted by Lowenstam, in Tennessee. The most spectacular molluscan fossils for isotopic analyses were those found in a stream bed called Coon Creek, in McNairy County in the western part of Tennessee [. I analyzed fossils from Coon Creek in that summer of 1969 in Urey’s old lab at the Institute on Ellis Avenue, before Apollo 11’s exotic rocks appeared on the scene.
A footnote in Urey, et al. (1951) confirms the paleontological adventures of Harold and Heinz [:
|“The specimens from Western Tennessee, Mississippi, Alabama, North Carolina, and South Carolina were collected by H.C. Urey and H.A. Lowenstam.”|
Urey, et al., indeed, praised the preservation of Upper Cretaceous mollusks from Coon Creek [:
|“The specimens from Tennessee were derived from the sandy marls of the basal third of the exposure on Dave Weeks’ Place, 3 ½ miles south of Enville, McNairy County, the type locality of the Coon Creek tongue of the Ripley Formation. Although belemnites do not occur in these deposits, depriving us of our reliable standard for comparison, the excellent shell preservation of all the molluscan elements with originally aragonitic shells, elsewhere in the outcrop areas preserved only as casts, implied exceptionally favorable burial conditions suggestive of preservation of original isotopic abundances.”|
Shindell does not describe Urey the fossil collector, Urey the detective, trying to understand why dinosaurs became extinct. Indeed, the biography by the Silversteins, published in 1971, describes Urey the paleontologist in this way [:
|“On a collecting trip with Heinz Lowenstamm [sic!] in the southern United States, Harold found that his friend could tell just by looking at a rock how old it was, while he often could not tell what was important and what was not.”|
This story is my way of remarking that Shindell’s biography of Urey falls short in presenting something about Urey as a scientist working as a scientist, Urey as a human enthusiastic about ideas, and especially more comprehensive explanations of Urey’s science.
Harold Urey was much more interesting than Shindell’s portrait of someone haunted by his Indiana upbringing in a restricted, isolated, religious community. As Joel Hildebrand remarked [: “Harold C. Urey is a phenomenon far too complex to be accounted for by a formula with only a few parameters.”
We’ll have to wait for a real scientific biography of Harold Clayton Urey to appear someday. There are many lesser figures in twentieth century science that have received appropriate, extensive explanations of their work for the fabled ‘interested public’. I’ll patiently wait for that next real biography of Urey, and instead comb through accounts of Urey to fill in my imagination about him.
Perhaps I will find a photograph of Harold Urey and his Jaguar. I wonder about that Jaguar’s color. Was it a convertible? [
|“To see the Harold Urey of today, roaring down the Moyenne Corniche of La Jolla in his snappy Jaguar, one might be struck by the vivid contrast with the early days of a young chemistry professor in the United States in the 1930’s. Yet Harold has not really changed his characteristics; he is simply in a hurry to get to work and he requires the fastest possible transportation for this purpose.”|
I never found that speeding, dashing Urey in Shindell’s biography. It’s those sorts of details that make a real biography become more than a litany of dates and facts, bringing their subject to life. — Edward J. Valauskas, Chief Editor and Founder, First Monday.
1. See, for example, A.C. Fabian, 2009. “Serendipity in astronomy,” arXiv 0908.2784 (19 August), at https://arxiv.org/pdf/0908.2784.pdf or R.M. Pearce, 1912. “Chance and the prepared mind,” Science, new series, volume 35, number 912 (21 June), pp. 941–956. Louis Pasteur’s remarks were made at a lecture at Université de Lille on 7 December 1854.
2. The first local science fair in my high school cafeteria was scheduled for March. If I succeeded at that event, I was sent to the regional science fair for students in a broader area, held on the campus of the Illinois Institute of Technology in April. If I was awarded a first place at IIT, my project headed to the state science exposition at Assembly Hall on the campus of the University of Illinois in Champaign in May. The regional and state events were sponsored and administered by the Illinois Junior Academy of Science.
3. George Gaylord Simpson and Anne Roe, 1939. Quantitative zoology: Numerical concepts and methods in the study of recent and fossil animals. New York: McGraw-Hill. The first edition; I now include Dr. Richardson’s copy with his distinctive book plate in my personal research library. That specific book changed completely my attitude towards mathematics; like Paul, the scales fell from eyes, except it was on the road from the Field Museum reading the book in the back of a CTA bus on a winter day, not the road to Damascus.
4. John Imbrie, 1956. “Biometrical methods in the study of invertebrate fossils,” Bulletin of the American Museum of Natural History, volume 108, article 2 (30 January), pp. 211–252; version at http://digitallibrary.amnh.org/handle/2246/998.
5. H.C. Urey, H.A. Lowenstam, S. Epstein, and C.R. McKinney, 1951. “Measurement of paleotemperatures and temperatures of the Upper Cretaceous of England, Denmark, and the southeastern United States,” Bulletin of the Geological Society of America, volume 62, number 4, pp. 399–416.
6. I had brashly written to Harmon Craig, a former student in the Chicago lab of Harold Urey, at the Scripps Institution of Oceanography in the spring of 1969 about my notion to re-examine Cretaceous mollusks from Coon Creek, examining their stable oxygen and carbon isotopic values. I had been collecting for some time by then a number of fossils from Coon Creek in Tennessee, and so I really thought about revisiting the isotopic work of Urey, Lowenstam, et al., to double-check their oxygen experiments and collect new data on carbon. Some oxygen data appeared in the literature, but not carbon. Craig thought it was a good idea and told me to contact Dr. Robert N. Clayton, who was in charge of Urey’s former lab at the Fermi Institute of Nuclear Studies. Dr. Clayton agreed that it was a good idea too and allowed me to spend time in the lab collecting data in the summer of 1969. There was not a lot of time for this work as the first Moon rocks were scheduled to appear in the lab in September 1969 for analysis.
7. Alvin and Virginia Silverstein, 1971. Harold Urey; the man who explored from earth to moon. New York: John Day Co.
8. Harold C. Urey, 1947. “The thermodynamic properties of isotopic substances,” Journal of the Royal Society of Chemistry, volume 1947, pp. 562–581; doi: https://doi.org/10.1039/JR9470000562.
9. Matthew Shindell, 2019. The life and science of Harold C. Urey. Chicago: University of Chicago Press, p. 130.
10. Harold C. Urey, 1948. “Oxygen isotopes in nature and in the laboratory,” Science, new series, volume 108, number 2810 (5 November), p. 491; doi: https://doi.org/10.1126/science.108.2810.489.
11. Shindell, p. 130.
12. U.S. Atomic Energy Commission. Bureau of Technical Information Extension, 1970. Corporate author headings used by the U.S. Atomic Energy Commission in cataloging reports. TID–5059 (tenth revised), p. 41.
13. A natural fission reaction was foreseen by Paul Kazuo Kuroda. Evidence was found in Africa that such an event occurred some 1.8 to 1.7 billion years ago in the Paleoproterozoic Era. See P.K. Kuroda, 1956. “On the nuclear physical stability of the uranium minerals,” Journal of Chemical Physics, volume 25, number 4, pp. 781–782; doi: https://doi.org/10.1063/1.1743058; F. Gauthier-Lafaye, P. Holliger, and P.–L. Blanc, 1996. “Natural fission reactors in the Franceville Basin, Gabon: A review of the conditions and results of a ‘critical event’ in a geologic system,” Geochimica et Cosmochimica Acta, volume 60, number 23, pp. 4,831–4,852; doi: https://doi.org/10.1016/S0016-7037(96)00245-1.
14. Shindell, p. 68.
15. Jacob Bigeleisen and Maria Goeppert Mayer, 1947. “Calculation of equilibrium constants for isotopic exchange reactions,” Journal of Chemical Physics, volume 15, number 5, pp. 261–267; doi: https://doi.org/10.1063/1.1746492.
16. Robert G. Sachs, 1991. “Maria Goeppert Mayer 1906–1972,” In: Edward Shils (editor). Remembering the University of Chicago: Teachers, scientists, and scholars. Chicago: University of Chicago Press, p. 326.
17. “Heinz Lowenstam interviewed by Heidi Aspaturian, June 21–August 2, 1988,” Archives, California Institute of Technology, p. 81, at https://collections.archives.caltech.edu/repositories/2/accessions/5017.
18. Harold C. Urey, 1973. “Cometary collisions and geological periods,” Nature, volume 242, number 5392 (2 March), pp. 32–33; doi: https://doi.org/10.1038/242032a0.
19. The original description of the Coon Creek fauna can be found in Bruce Wade, 1926. “The fauna of the Ripley formation on Coon Creek, Tennessee,” U.S. Geological Survey, Professional Paper, number 137; For a more recent assessment, see Dana Ehret, Lynn Harrell, and Sandy Ebersole (editors). “Paleontology of the Cretaceous Coon Creek,” Alabama Museum of Natural History, Bulletin, number 33.
20. Urey, Lowenstam, Epstein, and McKinney, 1951, p. 410.
21. Urey, Lowenstam, Epstein, and McKinney, 1951, pp. 410–411. This praise for the state of preservation of the Coon Creek specimens, as demonstrated by experiment, is even more apparent in H.A. Lowenstam and S. Epstein, 1954. “Paleotemperatures of the post-Aptian Cretaceous as determined by the oxygen isotope method,” Journal of Geology, volume 62, number 3, p. 229; doi: https://doi.org/10.1086/626160.
22. Alvin and Virginia Silverstein, 1971, p. 56.
23. Joel H. Hildebrand, 1964. “The air that Harold C. Urey breathed in Berkeley,” In: H. Craig, S.L. Miller, and G.J. Wasserburg (editors). Isotopic and cosmic chemistry: Dedicated to Harold C. Urey on his seventieth birthday April 29, 1963. Amsterdam: North-Holland, p. viii.
24. H. Craig, S.L. Miller, and G.J. Wasserburg, 1964. “Preface,” In: H. Craig, S.L. Miller, and G.J. Wasserburg (editors). Isotopic and cosmic chemistry: Dedicated to Harold C. Urey on his seventieth birthday April 29, 1963. Amsterdam: North-Holland, p. xi.
Copyright © 2020, Edward J. Valauskas. All Rights Reserved.
Urey conquers the universe, almost:
A review of The Life and Science of Harold C. Urey
by Edward J. Valauskas.
First Monday, Volume 25, Number 8 - 3 August 2020