A New and Improved Cavity Charge Projectile

Notes on explosives, October 2, 1942.

Major Ross, patent attorney for the Navy…said that perhaps I didn’t know that I was co-inventor in this invention – I do not remember having been told that I was. The invention is on an offset liner for cavity charge.

-Linus Pauling, February 8, 1952.

In February 1952, Linus Pauling was summoned by K.F. Ross, patent attorney for the Navy, to sign an oath and patent application form. The document was titled “Oath, Power of Attorney, and Petition,” and stated that Pauling and Martin A. Paul were the joint inventors of “An Offset Liner for a Cavity Charge Projectile.” Paul had already signed the same application on January 17, 1952. The document also stated that D.C. Snyder and K.W. Wonnell, attorneys affiliated with the Office of Naval Research, would manage the patent application.

When the inventors signed the patent application form, they also agreed to sell their invention to the Navy, which bought the patent from them for the sum of one dollar. It was furthermore stated that

The said Owners hereby agree to execute and deliver unto the Government, upon request, any and all instruments necessary to convey to the Government the full right, title, and interest in and to any substitutions, divisions, or continuations in part of said application.

In this way, Pauling simultaneously claimed inventorship and signed away ownership, as well as any other claims to the invention, with one stroke of his pen.


As a war-time scientist, Pauling was often called upon by the U.S. government to aid in the defense and protection of the country. During World War II he worked on projects as diverse as an oxygen meter and a human blood substitute. The offset liner for a cavity charge projectile, which Pauling worked on with Martin Paul, was one such project. The timing of the application, coupled with the absence of the cavity charge projectile from Pauling’s research notebooks, suggest that this was another of Pauling’s war work projects, but one that remained top secret until after the war.

The problem that the researchers endeavored to solve was the stabilization of gun-ejected explosive shells. The contemporary method of stabilization upon which Pauling and Paul were charged to improve was to spin the shells as they were ejected, which was not very efficient. For one, spinning the shells resulted in a fifty percent decrease in the force that the shells could deliver upon impact, as compared to a shell that does not spin. Working together, Pauling and Paul found a creative way to provide stabilization without lessening the impact that the shells could make on their targets.

Diagrams included with Pauling and Paul’s cavity charge projectile patent, November 1965.

The primary object of their project was to improve the penetrating power of a spin-stabilized, cavity charge explosive shell by inventing an improved cavity-charge shell. A cavity-charge shell includes a space around which the explosive is arranged, so that when the explosive detonates, the shaped cavity focuses and increases the detonation, thereby requiring a smaller amount of explosive to deliver a comparable amount of force.

One tactic used by Pauling and Paul in pursuit of increased efficiency was to change the shape of the cavity’s liner. The new and improved model of a cavity-charge projectile utilized a plurality of offset plane sectors which faced in the direction of the shell’s rotation, ostensibly causing the shell to be slowed less by spinning.

Further, in Pauling and Paul’s model, the liner for a cavity-charge projectile was constructed by dividing the conical surface of the cavity into sectors, and tilting each sector slightly towards the preceding sector. According to the duo’s patent, “45 degree steel cones of .062 inch thickness and sectioned in half and in quarters were respectively put together again with silver solder in such a way that adjoining edges were offset with respect to each other.” Upon impact, the force exerted by the explosive in the shell on these sectors would compensate for the slowing of forward motion caused by spin.

Pauling and Paul had been constructing cavity liners by dividing a conical surface into four separate sections which were then twisted or canted relative to each other. But the patent states that a die could be constructed which would enable the structure to be made in a single stamping. As to the efficiency of the offset cavity liner, “It can be seen that for speeds of rotation above about 130 r.p.m., the modified cones were far superior to the unmodified cones.”

Diagrams included with Pauling and Paul’s cavity charge projectile patent, November 1965.

Several variations in the invention emerged with slightly different cavity shapes and other modifications, but the patent concludes that the various versions of the invention all had key features in common. For one, all of them required the offset surface to face the direction of rotation of the shell. Likewise, they required “that there be a plurality of offset sectors where the amount of offset increases from apex to the base of the shell head portion.”

Pauling and Paul’s joint invention, “An Offset Liner for a Cavity Charge Projectile,” U.S. patent number 3, 217, 650, was patented on November 16, 1965, thirteen years after the original application was filed.

The Fate of Oxypolygelatin

An original container of 5% Oxypolygelatin in normal saline. 1940s.

During World War II, Linus Pauling, along with Dan H. Campbell and Joseph B. Koepfli, created a blood plasma substitute which they dubbed “oxypolygelatin.” This new compound seemed to be an acceptable substitute for human blood, but needed more testing to be approved by the Plasma Substitute Committee. Unfortunately when Pauling asked for additional funds to carry out more testing in 1945, he was denied by the Committee on Medical Research, which had been funding research up until that point.

By the time Pauling received more funding the war had almost come to a close, and it ended before oxypolygelatin got off the ground as an acceptable blood substitute. Likewise, the need for artificial blood was less pressing after the conclusion of the war. More information on the creation and manufacture of oxypolygelatin can be found in our blog posts “Blood and War: The Development of Oxypolygelatin, Part 1,” and “Pauling on the Homefront: The Development of Oxypolygelatin, Part 2.” Today’s post will focus on the patenting, ownership and uses of oxypolygelatin after World War II.

Pauling seemingly gave up on the project after 1946, mostly because widespread blood drives organized by the Red Cross and other organizations lessened the demand for artificial blood. In 1946 Pauling, Campbell and Koepfli decided to file for a patent on oxypolygelatin and its manufacturing process, which they then transferred to the California Institute Research Foundation with the stipulation that one of the inventors would be consulted before entering into any license agreement. They also noted that the Institute should collect reasonable royalties for the use of the invention, but only so much as was needed to protect the integrity of the invention.

The “Blood Substitute and Method of Manufacture” patent was filed December 4, 1946, and the Trustees of the Institute agreed to take on ownership of oxypolygelatin and the patent application in early 1947.

Notes by Linus Pauling on a method for producing oxypolygelatin. July 23, 1943.

Although it would appear that Pauling gave up on the oxypolygelatin project with the transfer of ownership, he still pushed for its manufacture years later. In October 1951, he wrote to Dr. I. S. Ravdin of the Department of Surgery at the University of Pennsylvania Medical School to inform him that oxypolygelatin was not being considered seriously enough by the medical world as a blood substitute.

Pauling insisted, “…that it is my own opinion that Oxypolygelatin is superior to any other plasma extender now known.” He likewise noted that it was the only plasma extender to which the government possessed an irrevocable, royalty-free license, so he could not understand why it was not being stockpiled and utilized.

As far as Pauling knew, only Don Baxter, Inc., of Glendale, California, was manufacturing oxypolygelatin. At this point the rights to oxypolygelatin were owned by the California Institute Research Foundation, not Pauling, and the Institute was not authorized to make a profit from it. Consequently, Pauling’s insistence on the production and usage of his invention can only be explained by a concern for humanity, coupled perhaps with an urge to see the compound succeed on a grander scale.

Later in 1951, Pauling continued to push for the usage of his invention, arguing in a February letter to Dr. E.C. Kleiderer that oxypolygelatin was superior to the plasma substitutes periston and dextran. In Pauling’s opinion “the fate of periston and dextran in the human body is uncertain…these substances may produce serious injuries to the organs, sometime after their injection.”

Oxypolygelatin, on the other hand, was rapidly hydrolyzed into the bloodstream and would not cause long-term damage. It was also a liquid at room temperature, unlike other gelatins, and was sterilized with hydrogen peroxide to kill any pyrogens (fever-inducing substances) while many other gelatin preparations failed because of pyrogenicity. One of the only problems with oxypolygelatin was that the chemical action of glyoxal and hydrogen peroxide could potentially produce undesirable materials, but the matter could be cleared up with further investigation.

It appears that Pauling’s interactions with Ravdin and Kleiderer did not result in the mass manufacture or marketing success of oxypolygelatin, but this did not deter Pauling from pursuing the matter many years later. In 1974, after visiting Dr. Ma Hai-teh in Peking, China, he sent Ma his published paper on oxypolygelatin, and discussed the possible production of the substance in China. He wrote to Ma, “I hope that you can interest the biochemists and pharmacologists in investigating Oxypolygelatin. I may point out that no special apparatus or equipment is needed.”

In reply, Ma expressed interest in oxypolygelatin and said that he had passed Pauling’s paper on to a group of biochemists, but that he was personally more interested in Pauling’s work on vitamin C. The rest of their correspondence focused primarily on the benefits of vitamin C, especially in the treatment of psoriasis.

In a 1991 interview with Thomas Hager, author of the Pauling biography Force of Nature, Pauling claimed, “I patented, with a couple of other people in the laboratory, the oxypolygelatin. I don’t remember when I had the idea of making oxypolygelatin. Perhaps in 1940 or thereabouts.” He added that it was not approved by the Plasma Substitute Committee, so it was not usable for humans, but was manufactured instead for veterinary use.

At the time of the interview, Pauling believed that oxypolygelatin was still being manufactured in some places, but was unsure of the details since there were many rumors floating around. According to him, the Committee on Plasma Substitutes did not approve his oxypolygelatin because it wasn’t homogenous; meaning that, on the molecular level, it included a range of weights. Pauling, however, believed that the range in molecular weights should not matter, since naturally occurring blood plasma includes serum albumin and serum globulin, whose molecular weights fall in a wide range anyway.

Joseph Koepfli

In 1992 Hager also interviewed Joseph Koepfli, one of the co-inventors of oxypolygelatin. Koepfli claimed that oxypolygelatin was at one time used by motorcycle officers around L.A. because they were the first to the scene of accidents. He also remembered that, in the early 1980s, Pauling had told him that oxypolygelatin was used for years in North Korea, but that no one was ever paid any royalties.

These and a few other rumors about oxypolygelatin circulated, but evaluating their worth is virtually impossible due to the secrecy surrounding wartime scientific work, as well as the scarcity and ambiguity of the surviving documentation. Judging from Pauling’s opinions though, what can be said is that perhaps if it had been pursued more vigorously, oxypolygelatin could have benefited the war effort and proven successful on a commercial level.

The Propellant and Burning Method

Notes re: high explosives and propellants. October 2, 1942.

We’ve discussed in the past the story of how the National Defense Research Committee was created by President Franklin Roosevelt in the summer of 1940, how Pauling joined in September of that year, and how he was assigned to work on hyper-velocity guns along with a group of other scientists. The committee Pauling belonged to was specifically charged with creating a high-performance propellant to use in hyper-velocity guns, and came up with experimental methods for studying powder combustion.

In 1943 Pauling began investigating a powder that resisted the destabilization to which contemporary powders were prone. He discovered that dinitrodiphenylamine was a more effective stabilizer than any other product used at the time. Pauling’s research team engineered several new powders, and his discovery led to a universal changeover from diphenylamine to dinitrodiphenylamine as the new compound was far safer to work with in industrial settings.

Adding to our previous writings on this subject, today’s post will focus specifically on the process of patenting Pauling’s “Propellant, and Method of Controlling the Burning Thereof,” filed June 18, 1945.

Because the research that Pauling and his team were conducting was directly related to the war, a secrecy order was issued by the Commissioner of Patents on Pauling’s application. As a result, certain documents related to the invention appear to have been either embargoed or destroyed, and some information on the subject has been lost.


Pauling’s NDRC authorization papers permitting work on explosives in warfare. May 1, 1944.

I patented, during the war, a class of composite explosives – propellants. And it may be that they are used, to some extent, now. I never got any royalties from that, because the government had an irrevocable royalty-free license, and nobody else was interested in the powder for propelling bazookas and things like that.

So said Linus Pauling in an August 1991 interview with Thomas Hager, author of the Pauling biography, Force of Nature. However, documents held in the Pauling Papers indicate some discrepancy from Pauling’s recollections.  On May 15, 1945, Pauling wrote a statement in which he agreed to assign to the California Institute Research Foundation his entire right, title and interest in the “Propellant and Method of Controlling the Burning Thereof,” OEMsr 881 Pat 1, along with any patent which the Foundation might file, as long as Pauling received a quarterly payment of 15% of the income from the invention. However, as Pauling stated in his interview with Hager, he never received royalties from his propellant invention, so either the California Institute Research Foundation never patented Pauling’s invention, or there was never any income.

Pauling’s patent attorneys, Lyon and Lyon, wrote a letter to the Commissioner of Patents in November of 1948 “in response to the Office Action of June 8, 1948,” in order to amend a patent application, and included a “remarks” section in which they listed all of the unique aspects of Pauling’s rocket propellant. According to them, “The only reference [in Pauling’s amendment] which is directed to a rocket or rocket propellant, is the British reference Piestrak.” (Piestrak was a scientist.) Lyon and Lyon continued, “It is inherently impossible for the propellant shown in this reference to function in the manner of applicant’s propellant…” In other words, Pauling’s propellant was different enough to where it would be impossible for Piestrak’s invention to replicate it.

Lyon and Lyon went on to list all of the different ways in which Pauling’s propellant was unique. According to them, only if the propellant shown by Piestrak were “arranged to burn from one end only and the central or (33) was filled with a propellant” and if the “slow burning cylindrical layers (34) were changed to fast burning cylindrical layers,” then the Piestrak propellant would be similar to Pauling’s. Further, in Piestrak’s invention, one cylindrical portion of the propellant would burn completely before the next one in order to create “spaced impulses,” while in Pauling’s, the portions were all fast-burning.

Next, they compared Pauling’s invention to an that patented by an individual named Maxim. Maxim’s invention “consists in providing in an explosive colloid, throughout its structure, uniformly arranged cells. These cells are shown in his preferred form as being voids.” The voids could also be filled with a fast burning powder, in order to expand the flame rapidly to the walls of the cells. However, Maxim’s methods did not apply to Pauling’s invention because Pauling’s product would be utilized in the confined space of a high-velocity gun.

The Maxim patent was issued in 1896, and was not meant for use in the same conditions as Pauling’s. Furthermore, Maxim’s powder could only function like Pauling’s on occasion and seemingly by accident. Likewise, Maxim’s black powder would not burn at the same rate as Pauling’s product, according to the attorneys.

Lyon and Lyon finished their letter to the Commissioner of Patents requesting favorable reconsideration of the application, which indicates that, in 1948, Pauling was still working on obtaining a patent for his rocket propellant.

Memo from Pauling to Lyon & Lyon, March 22, 1951.

Some three years later, on March 22, 1951, Pauling wrote a memo to Lyon and Lyon titled “Patent application on explosives.” In it, he compared his product to other inventions. According to Pauling, “In our case we are interested in controlling the burning rate – in conferring upon the major propellant material a burning rate other than that characteristic of it.” Pauling added that he was interested in controlling the burning rate by controlling strands, or by other special methods of manufacture of the propellant. He mentioned that another researcher named De Ganahl was not able to control the burning rate of his own propellant.

On March 7, 1952, Pauling received a letter from J.P. Youtz, business manager of the California Institute Research Foundation, informing him that the application serial no. 600,043, (Pauling’s rocket propellants patent) which had been pending in the Patent Office, had finally been rejected by the Examiner “in spite of the fact that there is more evidence to indicate your invention is patentable over the references cited.” April 12 was the deadline for an appeal.

From there, it is unclear as to whether or not Pauling’s claim to a unique rocket propellant and method of burning were ever acted upon. It is possible that the process was patented by Pauling and then passed on to the California Institute Research Foundation or the government. It is also possible that it was passed along to one of these entities and patented later. Or maybe it was not patented at all, and Pauling’s statement in 1991 was the result of a long, complicated legal process carried out during wartime and clouded by secrecy.

In any case, Pauling’s new method of creating rocket propellants and controlling their burning, and particularly his discovery of the stabilizing effects of dinitrodiphenylamine, resulted in an important contribution to safer working practices in the explosives manufacturing industry.

Patenting the Pauling Oxygen Meter

Series of diagrams of the Pauling Oxygen Meter. June 8, 1942.

The story of how Linus Pauling’s Oxygen Meter came into being has already been well documented on this blog.  In our previous discussion we outlined the workings of the oxygen meter itself, the improvements that were made, and the fate of the invention in the aftermath of World War II. Today’s post will add to that story by focusing on the uniqueness of Pauling’s invention and the means by which the Oxygen Meter came to be patented.

On October 7, 1940, a contract was drawn up between Caltech and the National Defense Research Committee (NDRC) for the development of the instrument. In a letter addressed to the NDRC, Pauling stated that, in view of the circumstances, and because his desire was to be of service to the country, he was willing to grant the government a non-exclusive, royalty-free license covering the entire invention throughout “the period of national emergency,” referring to World War II. He also expressed his desire that the National Defense Research Committee decide who would be given the rights to the apparatus at the end of the war.

Pauling wanted to file an application for a patent on his invention “inasmuch as it seems it will be of use in various fields other than that of national defense” – a correct supposition as it turned out. At the end of the letter, he commented that he wished to “proceed with the greatest speed in developing the instrument to the point of maximum usefulness in national defense.”

Irvin Stewart, secretary of the NDRC, wrote back and essentially told Pauling that, according to the patent clause, because he had created the invention after signing a contract with the Committee, the government was entitled to a royalty free license on the invention not only during the war, but throughout the life of the patent.

In a letter to Dr. James B. Conant of the NDRC, written February 15, 1941, Pauling next expressed a desire to patent the fundamental idea of his oxygen meter, “now that my oxygen meter will soon be put in use in other laboratories,” rather than the actual device itself. He mentioned the contract agreed to by the NDRC and Caltech, which stated that the Committee would have the sole power to determine whether or not a patent application should be filed. He also noted that “there are many uses to which the instrument might be adapted other than the original one.”

Pauling received an answer from Irvin Stewart on March 28, 1941, in which Stewart advised Pauling to apply for a patent on all of his developments that antedated the contract between the Committee and Caltech. Pauling replied that it was only after attending a meeting of the National Defense Committee in Washington, D.C. on October 3, 1940, that he initially learned of the need for an oxygen meter, and it was from this meeting that his ideas stemmed.  Pauling’s desire to patent his idea was running into roadblocks, but the uniqueness of what he had devised could not be denied.


The Pauling Oxygen Meter. approx. 1940.

Pauling’s “Apparatus for determining partial pressure of oxygen in a mixture of gases” was unique for many reasons. For starters, it was both light-weight and tough. It also made use of the fact that oxygen is a strongly paramagnetic gas, which means that its magnetism does not become apparent until it is in the presence of an externally applied magnetic field. Only a few gases other than oxygen are paramagnetic, but they are less susceptible to magnetism than is oxygen. For this reason, the apparatus was valuable in determining the oxygen content of a mixture of gases, except where other paramagnetic gases such as nitric oxide, nitrogen dioxide, and chlorine dioxide were present.

Because Pauling’s device was going to be used in war, the government wanted to limit the number of people who knew of its existence. The NDRC eventually granted permission for Pauling to reveal the nature of his invention to his patent attorney in Los Angeles, provided that he did not disclose the nature of the invention to anyone else. When Mr. Richard Lyon, of Lyon and Lyon, Attorneys, requested information on the assembly of Pauling’s invention in order to better research existing inventions like it, Pauling asked Dr. Reuben E. Wood, who worked on the device with Pauling, to fill in the attorney. It is from this exchange that we learn a bit more about what made the device special.

Wood told Lyons that Pauling’s device was novel in many ways. For one, Wood could not find any other reference to the use of the magnetic susceptibility of oxygen as a means of analyzing a mixture for it.  Also unique to the Pauling method were the facts that the composition of the gas sample was not altered by analysis, and that “the moving part of the device is actuated directly by the presence of the gas in the analyzing chamber.”

A similar apparatus, designed by Glenn G. Havens, had a recovery time of three minutes after being jarred or after a gas sample reading before it could be used again, while Pauling’s only needed one second. Another major difference between the two devices was that Pauling’s was portable while Havens’ was immobile and fragile.

Furthermore, Pauling’s model utilized a permanent magnet instead of an electromagnet, which meant that his magnet weighed less. Also, no source of electricity was required for the instrument to work except that required to operate a light bulb, which could be powered using a flashlight cell. All in all, Pauling’s model was more efficient, portable and dynamic than any competing instrument. Wood believed that all of these unique attributes were patentable.

Pauling filed a patent application on August 23, 1941. Having done so, he was promptly informed by the Department of Commerce of the United States Patent Office that the contents of his application “might be detrimental to the public safety of defense,” and was warned by the government to “in nowise publish or disclose the invention or any hitherto unpublished details of the disclosure of said application, but to keep the same secret.”

Later, Pauling discussed with the Office of Scientific Research and Development the procedure for obtaining a suitable manufacturer to produce his invention. The parties involved ultimately decided on Dr. Arnold O. Beckman and his organization as the likely purveyors, as they were familiar with instrument production problems through their experience in manufacturing parts for this and other technical equipment for laboratory use.

Reuben E. Wood. March 1948.

Dr. Wood, who had worked on the oxygen meter with Pauling, was also interested in patenting certain features which he had developed, so he wrote to the NDRC for permission to apply for a patent in March 1942. Important aspects which he improved upon were a “method of balancing the test body;” an improvement “which reduces the effect of temperature changes in the indication of the meter;” and “a method of selecting range of maximum sensitivity.” He later wrote to Richard Lyon enclosing four Records of Invention statements detailing his improvements on the Pauling Oxygen Meter.

However, in a letter to Captain Robert A. Lavender of the Office of Scientific Research and Development, Pauling communicated that it was not the intention of the California Institute Research Foundation to apply for patents on the inventions of Dr. J. H. Sturdivant and Dr. Reuben E. Wood. As concerned the Oxygen Meter patent, Wood was left out in the cold.


In March 1944 the Naval Research Laboratory of Washington, D.C., sent a confidential statement to the Chief of the Bureau of Ships in which it was stated that

this Laboratory has been interested in the development of an oxygen indicator suitable for service on submarines. The most satisfactory instrument has appeared to be the Pauling Oxygen Meter and a detailed study has been made of its operating characteristics, ruggedness, dependability and general efficiency with very promising results.

The letter also noted that the Pauling Oxygen Meter was found to be superior to a similar instrument – namely, the one created by Havens.  The efficacy of Pauling’s invention was becoming manifest.  As he himself had predicted, the device would be of use for both the war effort and in peace time.

Finally, after much brainstorming and years of collaboration, hard work and improvement, and after having been proven exceedingly useful during World War II, Pauling’s Oxygen Meter was patented on February 25, 1947, some five and a half years after the initial application was submitted.

The Palmer Committee

Vannevar Bush, 1940s.

Linus Pauling’s experimental work for the government came to an end with the closure of the oxypolygelatin program. Despite that, his association with the Office of Scientific Research and Development (OSRD) continued. In late 1944, President Franklin D. Roosevelt contacted Vannevar Bush, director of the OSRD, and requested a report on the future of science in the United States. In response, Bush organized his colleagues into committees and requested that they consider the problem of funding American science and, eventually, offer recommendations.

Pauling, along with dozens of others, was selected to serve as an adviser. A result of his experience with the Committee on Medical Research, oxypolygelatin, and the oxygen meter, Pauling was assigned to a medical advisory committee chaired by Walter W. Palmer, a professor of medicine at Columbia University.

Once the committees had been organized, Bush plied them with discussion topics, asking them to consider the implications of government support for the sciences. Pauling himself was an enthusiastic advocate of government-funded research. He believed that public dollars were the best way to promote scientific growth and allow scientists to make progress in fields that didn’t promise an immediate financial return.

Science leading up to World War II had been funded almost exclusively by universities and corporations, both vying for the prestige and monetary profit that would result from marketable discoveries. Because pure science couldn’t promise the same economic returns that commercial science could, funding for university labs was significantly lower, frequently leading researchers to abandon their professorships in favor of positions in the private sector. Pauling believed that the most efficient way to address this problem was through a governing body empowered with the ability to provide support according to a proposed project’s scientific merit. Funding would be provided with an eye toward the value of the research in relation to the general body of scientific knowledge rather than its potential commercial worth.

Ultimately, the Palmer Committee concluded that no existing federal agency would be able to assign grants without some degree of specialization bias creeping into its process. As a result, Palmer’s group advocated, for one, the creation of a new agency with specific focus on supporting scientists from different fields of medicine and governed by medical experts spanning multiple fields.

Bush was troubled by the committee’s assumption that a separate organization should be created to oversee and fund medical research. Bush’s career had been severely complicated by the lack of cooperation between Washington’s many bureaucracies, and he was loathe to support what he saw as a further bloating of the system. As a result, he took the best of the Palmer Committee’s ideas – the governing body of experienced researchers – and combined them with his own ideas and those of his other colleagues. In the summer of 1945, Bush delivered his treatise on post-war science, “Science: The Endless Frontier,” to Harry S. Truman, President Roosevelt’s successor. In it, Bush recommended the creation of a National Research Foundation (NRF) charged with providing monies to researchers, including medical researchers, according to scientific merit.

Presidential Medal for Merit. Awarded to Linus Pauling by President Harry S. Truman, February 2, 1948.

For nearly five years, politicians and lobbyists battled over the details of this so-called “National Research Foundation.” Funding, focus, and structure were all issues that kept the organization from taking shape. To further complicate matters, while Bush’s proposal was stymied by politicians, other national science organizations like the Atomic Energy Commission and National Institutes of Health became major contributors to the “big science” movement, thus reducing potential NRF jurisdiction.

After years of debate, a consensus was finally reached and on May 10, 1950 President Truman signed the National Science Foundation Act. This legislation created the National Science Foundation (NSF) which was directed by a 25-person National Science Board that included 24 part-time members and an executive officer as appointed by the President. For the first several years of its existence under the direction of the physicist Alan T. Waterman, the NSF was virtually destitute thanks to the expense of the Korean War. Nevertheless, the organization persevered and by the mid-1950s was equipped with a $100 million budget.

After his work with the Palmer committee, Pauling quietly left the OSRD and returned to his personal research agenda at Caltech. His contributions and departure did not go unnoticed by OSRD officials, however, and he was officially recognized by the War Manpower Commission, the NDRC and OSRD, the War Department, and the United States Navy Bureau of Ordnance. In 1948 he was awarded the Presidential Medal for Merit for his wartime contributions. The war chapter of his career concluded, Pauling continued on with his biochemical research and began a campaign against nuclear weapons, ultimately earning two Nobel prizes and becoming one of the most influential chemists and peace activists of the 20th century.

Invisible Inks

Test screed developed as part of a research program on invisible inks. November 14, 1945.

By 1944 the oxygen meter and propellant projects were running smoothly with only minimal oversight from Pauling.  With more free time available to him, he began looking into new lines of research.  That year, he was contacted by Arthur Lamb, a Harvard professor, regarding a new line of inquiry.  During World War I, Lamb had developed invisible inks for the U.S. government.  He was restarting his work with inks and wanted Pauling’s help.  And so it is that, in September 1944, Linus Pauling became an official investigator in the Office of Scientific Research and Development’s invisible inks project.

The goal for Pauling and his team was to create a series of inks that were truly invisible and could only be developed by a limited number of chemicals. From September to October 1944, Dr. George Wright, William Eberhardt, and Frank Lanni made preliminary examinations of potential methods for developing invisible inks, the specifications of which were not defined in Pauling’s official reports to the OSRD. Once the preliminary tests were complete, Pauling and his team began a wide range of experiments, testing a variety of potential approaches for creating secret inks.

The team began with possible protein-based inks. They applied various proteins including rabbit serum, human saliva, and homogenized milk to standard typing paper. Then, after steaming and ironing the treated page, the team painted it with a mixture of ink, acetic acid and sodium chloride. The combination of acid and ink caused the protein to darken slightly, rendering it legible in well-lit conditions.

The group also tested non-organic inks such as diluted potassium iodide. After drying, the test screed was painted with gold chloride, rinsed, and then treated with a substance referred to only as “the silver physical reagent,” a compound protected by the Office of Censorship.

Page of test screeds developed as part of a research program on invisible inks. 1945.

Pauling and his team needed to find a better way to protect invisible inks from being identified when intercepted by enemy forces. To this end, the team turned its focus toward substances with high immunological specificity; that is, organic substances that reacted with only a limited number of other compounds. The team began with a polysaccharide gum distilled from a bacterium responsible for lobar pneumonia in humans. (Because the gum was largely non-reactive with other chemicals, the paper it was printed on hid it well.) The ink was then masked with an additional coating of a wax-like substance to prevent all but the most immunologically-specific chemicals from developing it. While tedious, the process was effective.

In addition to the use of polysaccharide gum, Pauling and his group examined antibodies and antigens in the hope that they could be used to create inks. In a report to the OSRD, Pauling explained that when a foreign protein (antigen) is introduced to an animal’s bloodstream, the animal produces a highly specific complementary protein (antibody) to neutralize it. When the two proteins combine, they form a stable protein-protein pair.

Initial tests of the solution suggested that the antibody-antigen combination could be highly effective. Unfortunately, as the researchers began practical testing they found it extremely difficult to develop the protein-protein pair without staining or otherwise rendering illegible the paper on which the ink was printed. What’s more, some of the antigens could be developed with non-organic chemicals, greatly reducing their security. Ultimately, the antibody-antigen ink was impractical. Pauling suggested that a few changes might be made to the process, but no record of additional experimentation appears in the Pauling Papers.

Despite having achieved some measure of success with a variety of inks, Pauling suggested that the project might be pushed even further. As he explained in a report,

From the offensive standpoint, it might be considered that the development by the new techniques of substances which are not detectable by the present methods might be useful as a basis for offensive methods.

While Pauling left no traces suggestive of his engaging in this process, it is at least plausible that he and his team did in fact note and retain a number of potential developers for future scientists to test.

In all Pauling and his team created or enhanced around a dozen different ink-developer combinations, ranging from improvements on existing camphor-based Presto pencils to complex processes using albumin, gypsum, and the catalytic reduction of silver. The project was closed with the publication of the “Final Report on Biological SW” dated December 31, 1945.

Hydrogen Peroxide

Linus Pauling in the laboratory. 1940.

I am planning to carry out during the next few days some experiments on the resistance of concentrated peroxide to shock by detonators and by rifle bullets, and I shall let you know the results of the experiments.

-Linus Pauling, letter to T. K. Sherwood, November 14, 1940.

Beginning in early 1940, Dr. Paul A. Giguere, a visiting researcher from Laval University, began a study of the properties of concentrated hydrogen peroxide at the Caltech labs. Under Pauling’s watch, Giguere spent several months performing electron diffraction analyses on samples of hydrogen peroxide and hydrazine. By November, the testing had been completed and the two men wrote a brief report on their findings. Pauling, already deeply involved in the development of the oxygen meter for the National Defense Research Committee (NDRC), felt that his and Giguere’s work might net the Institute another war research contract.

On November 14 he sent Thomas K. Sherwood, his primary NDRC contact, an enthusiastic letter detailing the initial findings. One early indication of Guigere’s work was that hydrogen peroxide might be used to absorb shock from explosives or rifle bullets. He also thought it possible to develop a means of controlling the evolution of hydrogen peroxide, suggesting that it could be used to produce oxygen for respirators. The laboratory intended to begin shock resistance tests immediately so that a clean set of data might be prepared, pending Sherwood’s response.

Pauling received an encouraging reply from Sherwood, but it is unclear at what point further work on the hydrogen peroxide project began. Fully two months after the initial correspondence exchange, Sherwood sent a letter to Caltech requesting a progress report from Pauling. In response, Pauling appears to have sent two letters: one detailing work on the oxygen meter and the other containing information on the hydrogen peroxide project. Unfortunately, it seems Pauling’s archives are incomplete as only the first letter remains extant. Whatever information may have been included in the second letter is lost, though we do know that Sherwood responded positively and sent Pauling data on hydrogen peroxide as a chemical fuel for combustion engines.

Thomas K. Sherwood, ca. 1960s. National Academy of Sciences image.

Bizarrely, following this last communication from Sherwood, no further mention of the hydrogen peroxide problem appears in Pauling’s papers until February 1943, in the form of a letter from Giguere demanding to know why Pauling’s article – presumably on his hydrogen peroxide research – had never been published. In response, Pauling reported that he and Dr. Verner Schomaker had only recently completed the manuscript and would send it on to Giguere shortly. Interestingly, this report too appears to be absent from the archives. What’s more, only a single page of hydrogen peroxide research remains in Pauling’s research notebooks.  This page details the decomposition of hydrogen peroxide in blood – a tantalizing entry that gives little indication of the nature of his research.

It is surprising that Pauling, who maintained comprehensive records of his scientific activities, possessed so few notes on his work with hydrogen peroxide. One might speculate that perhaps certain of the materials related to this project were turned over to higher authorities within the government, as has been confirmed with other projects in which Pauling was engaged.

Whatever the cause may have been for this lapse in the record, it seems plausible that Pauling’s early hydrogen peroxide work did have some long-term consequences.  In 1942 Pauling began work on a war research project on the development of a plasma substitute eventually known as oxypolygelatin. This work was spawned from his private Caltech-based research into bovine gamma-globulin, possibly the cause of Pauling’s initial experiments with blood and hydrogen peroxide. It may have also been this initial investigation that led Pauling to use hydrogen peroxide in the creation of oxypolygelatin.

Unfortunately, without letters, reports or laboratory data to review, it is impossible to know exactly what Pauling’s hydrogen peroxide research entailed or how it affected his later research. It seems then, that this particular project will remain one of many small mysteries in Pauling’s life.