Chairing the Division During the War: Maintaining Security and Revising the Curriculum

Linus Pauling, 1942

[Pauling as Administrator]

As chairman of the Division of Chemistry and Chemical Engineering at the California Institute of Technology, Linus Pauling was tasked with focusing, administratively, on the big picture while also maintaining and protecting ongoing research. This was especially so with confidential work being conducted during the Second World War.

One early incident that required Pauling’s input came about near the end of Fall 1942 when Foster Strong, a physics instructor, observed an undergraduate student using a master key to enter unauthorized rooms in the Crellin Laboratory. Upon catching him, Strong broke the key while giving the student, according to Pauling’s subsequent report, a “severe lecture about the seriousness of the offense.” As it turned out, the lecture did not take.

The following February, Elizabeth Swingle, the division’s stockroom keeper, saw this same student using a key to enter the stockroom. The first time she caught him, the student claimed that he was only able to get in because Swingle had left the door open. When Swingle later walked in on the student – this time accompanied by others – in the stockroom after hours, Swingle went to Pauling. She described this second encounter in a formal report, noting that “a look of surprise and a flush spread over [the student’s] face when he saw me.”

When confronted by Pauling, the student originally said that he had copied another student’s key to obtain entry. Later he admitted that this was a lie, and that he had originally had two keys made. Being in possession of an unauthorized master key was, in Pauling’s judgement, a “serious offence” because of the “confidential nature of some of the work being done” at the labs as part of the war effort. Pauling directed that the student no longer work in the Crellin facility any more.

Just over a month later, Swingle found the Crellin stockroom unlocked on a Monday morning, despite having locked the door on her way out the previous Saturday. Upon inspection, she found that sixty liters of an anesthetic, absolute diethyl ether, and 150g of vanillin, an extract of vanilla, were missing. A few weeks later, Swingle found two keys left on a table by the stockroom; one would permit entry into the room.


At the next division council meeting, it was decided that this series of events was serious enough as to merit the hire of a security guard to keep an eye on both Gates and Crellin during nights and weekends. It was also decided that identification cards would be issued to those with clearance to access the building after hours. Master keys would be restricted to faculty members only, and the provision of additional master keys to others would be up to Pauling. Elizabeth Swingle, along with two other women, had their master key privileges revoked.

At the beginning of June, the Institute also came to a decision on a just punishment for the undergraduate whose activities had caused such concern. It was found that the student had violated Caltechs honor system and that he would be placed on disciplinary probation for the remainder of his time as an undergraduate. This meant that he could not hold elected office or work on campus.

Three days after the decision had been rendered, Swingle reported to Pauling that someone had left the stockroom a mess. “Some chemical had been spilled on my desk leaving the finish injured,” she wrote. In addition, “there was a yellow colored chemical on the floor, in the waste paper basket, and on two towels.” Upon further examination, Swingle determined that the yellow chemical was quinone, and subsequently found that 100 grams of the substance was missing from the stockroom’s inventory. Pauling asked around, inquiring if any research groups had been using quinone and if any lab workers may have removed it without filling out a charge slip. None of the colleagues with whom he inquired were using the chemical at the time.

By July the ID badge system had been put into place, restricting access to Gates and Crellin between 6:00 p.m. and 7:45 a.m. on weekdays, and between 1:00 p.m. Saturday and 7:45 a.m. Monday. A year passed without incident.

Then, in 1944, Biochemistry professor Arie Haagen-Smit saw a research assistant for the NDRC-Chem-13 project enter a laboratory in the Kerckhoff basement where confidential and secret war work was being carried out. Haagen-Smit confronted the researcher and asked how he got in. He replied that there were “a number of keys around which open practically all the doors on campus.” A friend who was a graduate student in mathematics had given him the key to see if there was any equipment in the restricted lab that he could use for his research in NDRC-Chem-13. In response, Pauling again directed that limitations be placed on master keys and the division encountered little trouble thereafter.


As World War II came to an end, the division recognized a pressing need to reassess its graduate offerings, which had been rapidly updated amidst the pressure to meet wartime demands. One area that had suffered as a result of this update was organic chemistry, a point that was emphasized to Pauling by his colleague Edwin Buchman. Noting that there was a lack of instruction and organization when it came to graduate training in organic chemistry, Buchman requested that Pauling form a committee to define policies around research and teaching in the division.

Pauling also worked beyond the division level to update graduate programs across the Institute through his committee assignments. A member and, on occasion, the acting chair of the Graduate Committee on Post-War Policies, Pauling also served on the Faculty Board and Curriculum Committee. During one meeting, Pauling became especially intrigued by physicist E.C. Watson’s idea that Caltech accelerate its graduate work through the implementation of new teaching methods. By doing so, Watson saw the potential for Caltech to repeat its successes from the 1920s, the decade during which they had initiated their current system, becoming an “excellent graduate school” frequently “copied by other technical schools” in the process. On a practical level, this would mean dropping applied courses for which there had been an urgent deman during the war, such as industrial design. Though expressed with the intention that they be applied across the Institute, Watson’s ideas lined up well with what Pauling had in mind for the division that he oversaw.


Another component of the graduate program requiring scrutiny was Caltech’s masters degree offerings. Differing from many other technical institutes, Caltech’s Master of Science degree was essentially a continuation of undergraduate work, with the degree awarded following the completion of a fifth year. To attract students to the program, Pauling proposed implementing a scholarship program similar to that offered by the Massachusetts Institute of Technology, which covered tuition and provided a stipend of between $700 to $1,000 for eight months of study. Much later, in the spring of 1953, Pauling suggested further expanding the program by lowering a barrier to entry. Pauling’s idea was that Caltech treat its undergraduate seniors as first year graduate students, thus allowing them to focus more on research and to gain entry to laboratory space.

As part of their fifth year, master’s degree-seeking students at Caltech were required to take one course in the humanities: an introductory survey of English literature, history, philosophy, or economics. During a December 1944 meeting of the Graduate Committee on Post-War Policies in which he was Acting Chair, Pauling pointed out that the addition of a humanities requirement had been made in 1928 as a result of faculty action and was “not a part of the general policies of the Institute as expressed by the Trustees.” Pauling’s comments came on the heels of a previous committee recommendation that the Board of Trustees “abolish” the humanities requirement for the master’s degree.

The humanities requirement was brought up again two weeks later, but no decision could be reached. At the meeting that followed, Pauling put forth an alternative idea — that the Institute consider adding courses in the history and philosophy of science. The committee agreed enough with this sentiment to recommend that the Division of Humanities look into hiring someone in the field. A few years, Caltech brought aboard Rodman W. Paul, whose research interests were in the histories of mining and agriculture. Student enthusiasm for coursework of this kind was such that Caltech eventually created an entire program in the history and philosophy of science.

Pauling’s Last Year as a Grad Student

Ava Helen and Linus Pauling, 1924.

Ava Helen and Linus Pauling, 1924.

[Part 3 of 3]

Pauling’s final year of graduate school at the California Institute of Technology, 1924-1925, was quite busy.  During this last phase of his student experience, Pauling’s primary research interests centered on hematite, corundum, and beta-alumina, though a great deal more professional and personal growth can be traced to this time in the budding young scholar’s life.

In his work on corundum and hematite, Pauling was assisted by Sterling B. Hendricks, a Texan who had received his master’s degree from Kansas State in 1924 was now in Pasadena, working on his PhD.  Hendricks became a close associate and personal friend of Pauling’s and, with their mentor Roscoe Dickinson away on a research trip, Pauling became Hendricks’ unofficial adviser. Such was Pauling’s influence that, later in life, Hendricks would come to consider himself to be “Linus’s first student.”

Together, Pauling and Hendricks worked on a theoretical paper that pieced together much of the work that they had completed over the previous year and a half. The paper was published in the Journal of the American Chemical Society (JACS) in March 1926 (nearly a year after Pauling had completed his PhD) and titled “The Prediction of the Relative Stabilities of Isosteric Isomeric Ions and Molecules.”  The paper was a milestone in that it was Pauling’s first paper devoted solely to the subject of the chemical bond.

It was not, however, the first paper that Hendricks and Pauling had co-authored. In 1925 the duo worked together to publish two sets of crystal structures: “The crystal structures of hematite and corundum” (March 1925) and “The crystal structures of sodium and potassium trinitrides and potassium cyanate, and the nature of the trinitride group” (December 1925).  During his last year of grad school, Pauling also collaborated with his friend and former roommate, Paul Emmett, on an X-ray determination of the crystal structure of barite.  Their article, which was published in JACS in April 1925, is another example of Pauling’s work that corrected previous published structures.

Peter Debye, 1926.

Peter Debye, 1926.

On top of the research that he was doing on crystal structures, Pauling also toyed with an idea in which he applied the Debye-Hückel theory, which was used to determine the energy coefficient of ions in dilute solutions. When he learned of this work, A.A. Noyes invited Peter Debye, who was based in Switzerland, to visit Caltech, in part to have him discuss his theory with Pauling. And although Pauling never published his original idea, in July 1925 Debye and Pauling did co-author a different paper, “The Inter-Ionic Attraction Theory of Ionized Solutes.  IV.  The Influence of Variation of Dielectric Constant on the Limiting Law for Small Concentrations.”  Appearing in JACS, the article was a contribution to a larger series published by the journal on the inter-ionic attraction theory of ionized solutes.


Later on in his life, Pauling developed a reputation for staying on top of the latest findings and issuing an informed opinion on a wide range of scientific topics.  This character trait was likely spurred by an experience that he had as a graduate student.

Early on in his graduate career, one of Pauling’s more influential professors, Richard C. Tolman, posed to him a question about diamagnetism. Pauling responded that diamagnetism was just a general property of matter, a lackluster reply that made clear that Pauling had not stayed current with the literature. Tolman kept questioning Pauling for more specific details until Pauling finally answered, “I don’t know.”  For this he was reprimanded by a Caltech post-doc who told him, “You are a graduate student now, and you’re supposed to know everything.” This was advice that Pauling took to heart and that made a big difference throughout his career in science.


The Paulings, 1925.

The Paulings, 1925.

Nearing the end of his graduate school tenure, Pauling read G.L. Clark’s paper on uranyl nitrate hexahydrate and, as he went, he corrected it.  This was a continuation of the critical reading habits that he had first developed at Oregon Agricultural College and had continued to hone by lantern light while working for the Oregon Highway Department the summer prior to his enrollment at Caltech. It was likewise a practice that he would continue throughout his career: closely reading papers and correcting errors, often by letting the author or publisher know what he had found.

By this time, with Roscoe Dickinson away, Pauling had taken up some of his mentor’s responsibilities in the lab and, as with Sterling Hendricks, was serving as an ad hoc advisor to several students.

Likewise, with Dickinson gone, Pauling began to develop his own techniques to aid in crystal structure determinations. A methodology that was quite different from the formal instruction that he had received, Pauling’s approach used atomic sizes and chemical behaviors to approximate reasonable structures for molecules.  After determining these possible structures, Pauling then used X-ray data to eliminate unlikely possibilities and to isolate the best possible structure for a particular substance.  As it turned out, this approach to scientific inquiry already had a name, the stochastic method, and Pauling ultimately put it to effective use across many different disciplines.


Linus Jr. and Ava Helen, 1925.

Linus Jr. and Ava Helen, 1925.

Pauling’s last year as a grad student also included big changes in his personal life.  After marrying in the summer of 1923, Ava Helen Pauling moved to Pasadena with her husband and kept house while he finished his degree. In the early years of their marriage, these duties also routinely included helping “keep house” in the laboratory, particularly by recording data and taking notes. Pauling’s research notebooks from these years are full of her handwriting, even including one note reminding Linus that she loved him.

In the midst of all his coursework and research, and as Pauling was wrapping up his last Winter term at Caltech, another big change came about when the Paulings’ first child, Linus Jr., was born on March 10, 1925.  By this time, Ava Helen was mostly excused from laboratory duty and focused her energies primarily on raising her children (ultimately there would be four) thus creating an atmosphere at home in which Linus could be as productive as possible.


Graduation day, 1925.

Graduation day, 1925.

Linus Pauling completed his PhD in chemistry in June 1925, tacking on minors in physics and mathematics as well. His dissertation, titled “The Determination with X-rays of the Structure of Crystals,” consisted of a compilation of articles that he had previously published with little more than new pagination connecting them together as a whole.

The summer after graduation, A.A. Noyes helped Pauling to secure a research fellowship that would enable him to stay at CIT and complete a research study on complex fluorides.  Pauling continued in this vein for the next eight months, during which time he began to make plans to leave Caltech to study as a post-doc at Berkeley, where he thought he might pursue a new set of experiments in G.N. Lewis’ lab, using funding from a National Research Fellowship that he had received.

Not wanting to lose Pauling to Berkeley and Lewis, Noyes managed to arrange for Pauling to remain in Pasadena in order to complete additional unfinished work on crystal structures.  Fortunately for Noyes, at the end of 1925, when the Guggenheim Fellowships were announced, Pauling was finally chosen for funding, having at last reached the program’s required minimum age.  At Noyes’s urging, Pauling resigned from his National Research Fellowship once he had received the good news from the Guggenheim Foundation. From there, Linus and Ava Helen took an important trip to Europe and ultimately returned to Caltech, their institutional home for the next thirty-six years.

Pauling Becomes a Researcher

Roscoe Dickinson, 1923.

Roscoe Dickinson, 1923.

[Part 2 of 3 in a series investigating Linus Pauling’s life as a graduate student]

As a graduate student at the California Institute of Technology (CIT), Linus Pauling tailored a research program that was focused on the properties of matter, with a particular emphasis placed on molecular structure. This interest and the techniques that he learned would shape Pauling’s scientific thinking for the rest of his life.

Pauling’s focus on the theoretical, and his questioning of why processes move forward as they do or why structures are built as they are, was in keeping with contemporary trends in physical chemistry. Pauling enrolled at Caltech with a strong desire to learn more about the discipline of physical chemistry and his early mentor, Caltech chemistry chair A.A. Noyes, encouraged him to build up his background in x-ray crystallography to further enable this pursuit.

When Pauling began classes in September 1922, he also began his research in x-ray crystallography under the direction of his major professor, Roscoe Gilkey Dickinson.  Not much older than Pauling and a recently minted PhD himself, Dickinson would soon become Pauling’s friend. Within weeks, Pauling began receiving invitations for dinners at the Dickinson house and was soon spending the odd weekend on camping trips with Dickinson and his wife.  After Ava Helen and Linus were married, she too joined in these social gatherings.

Dickinson and Pauling worked closely together for most of Pauling’s first year of grad school, but once Pauling had mastered the techniques necessary to prepare his own research, he mostly moved without Dickinson’s direct supervision. In a 1977 interview, Pauling recalled that Dickinson “was remarkably clear-headed, logical, and thorough” while working in the lab.  And as for the research,

Fortunately the field of x-ray diffraction was in an excellent state in that the procedures were rather complicated but they were thoroughly logical, [and] consisted of a series of logical tests.

The rigor and the logic that were fundamental to the field both pleased Pauling immensely.  And before long, the prodigious young student had moved beyond the expertise of his mentor and had begun to conduct original research that was outside of Dickinson’s own capability. In fact, Pauling’s acumen in the lab and facility as an x-ray crystallographer advanced so rapidly that, by his own recollection

…after about three years…I was making structure determinations of crystals that the technique was not powerful enough to handle, by guessing what the structure was and then testing it.


X-ray apparatus at Linus Pauling's desk, Gates Laboratory, California Institute of Technology. 1925.

X-ray apparatus at Linus Pauling’s desk, Gates Laboratory, California Institute of Technology. 1925.

But in his earlier days, Pauling still needed some help. During November and December of his first year as a graduate student, Pauling prepared approximately twelve crystals and attempted to analyze them using x-rays, but none of the crystals yielded images sufficient enough to make a structure determination.

At this point, Dickinson stepped in and directed Pauling to the mineral molybdenite (MoS2), in the process showing him how to take an adequate sample, mount it, and analyze it using x-ray crystallography. This assistance in hand, Pauling was able to determine the structure of the crystal and Dickinson returned to his own work, confident in his feeling that Pauling was capable of doing the crystallography himself.

Soon after completing the experiment, Pauling was confronted by a very different type of confusion. With a successful structure determination in hand, he assumed that the next step would be to publish the work. So too did he assume that Dickinson would provide him with more direction, but he found that none was offered.  As such, Pauling wrote up his findings and presented them for review to his major professor.

Not long after, A.A. Noyes summoned Pauling to his office and carefully explained to the young graduate student that he had written up a paper with only his name on it and in the process had failed to acknowledge the crucial help that Dickinson had provided. Chagrined, Pauling revised the paper and listed himself as a second author, behind Dickinson. The experience proved to be an important one for Pauling, who was reminded early on of how easy it can be to minimize or discount the role that colleagues can play in one’s own research.


Molybdenite model, side view.

Molybdenite model, side view.

By the end of April 1923, Dickinson and Pauling had submitted their paper on the structure of molybdenite to the Journal of the American Chemical Society (JACS); it was published in June of that same year.  Together they had found the simplest crystal structure of molybdenite – which contains two molecules in a hexagonal unit – based on Laue and spectral photographs, and using the theory of space groups.  Although he published a piece on the manufacture of cement in Oregon while he was in undergrad at Oregon Agricultural College, the molybdenite paper was Pauling’s first true scientific publication.

Later that year, Pauling arrived at another milestone by publishing his first sole-author paper, one in which he described the structure of magnesium stannide (Mg2Sn) as determined, once again, by using x-rays. The paper was a huge accomplishment for another reason as well: the x-ray processes used by Pauling had never been successfully deployed for the study of an intermetallic compound before.  And even though this was his first single author paper, Pauling still made sure to thank Roscoe Dickinson in his conclusion, taking pains to avoid another scholarly faux pas.  He would continue in this practice throughout his graduate career.


Richard Tolman, 1931.

Richard Tolman, 1931.

“The crystal structure of magnesium stannide,” was one of eight articles that Pauling published during his grad school years – he completed an impressive total of six structures before receiving his doctorate. Having authored these articles, Pauling found himself on the forefront of a shift in physical chemistry: as crystallography advanced, it was becoming increasingly clear that the properties of specific compounds were based on their structures, which could now be described with mounting confidence. Indeed, several of Pauling’s articles included reevaluations of existing structures, with revised explanations as to why the structures in question had not complied with the new data that Pauling collected.

One such article was “The Entropy of Supercooled Liquids at the Absolute Zero,” which Pauling wrote with CIT faculty member Richard C. Tolman.  In their paper, the two authors corrected an earlier claim made by Ermon D. Eastman, a professor of physical chemistry at Berkeley, who had stated that complicated crystals (those with large unit cells) have greater entropy at absolute zero than do simple crystals. Using statistical mechanical techniques, Pauling and Tolman were able to show that, at absolute zero, the entropy of all perfect crystals, even those with large unit cells, also has to be zero.


Detail from 'Atombau und Spektrallinien' containing x-ray diffraction images.

Detail from ‘Atombau und Spektrallinien’ containing x-ray diffraction images.

Pauling had become familiar with Tolman through a different means. During his third term at Caltech, Spring of 1923, Pauling took Tolman’s course in advanced thermodynamics, an experience that boosted his subsequent interest in quantum theory. It was also during this period that he read Arnold Sommerfeld’s Atombau und Spektrallinien (Atomic Structure and Spectral Lines) and began to be exposed to cutting edge research in quantum theory through the numerous physics and chemistry research colloquia hosted by Caltech.

Sommerfeld would become a lasting influence on Pauling’s life and Pauling would eventually study with him in Germany while there on a Guggenheim Fellowship in 1926-27. But well before then, in 1923, Sommerfeld visited CIT to talk about his work with the new quantum theory. As an aid to his lectures, Sommerfeld used crystal models that he brought from Germany, which he hoped would help him to better explain this complicated work. Afterward, Pauling felt emboldened enough to to show Sommerfeld some of the models that he himself had made in the course of his own research; models that turned out to be much better than those constructed by Sommerfeld.