The stench of war

In 1944, while scientists feverishly built weapons designed to kill Nazis, one MIT graduate focused on waging psychological warfare. Ernest Crocker, Class of 1914, a chemical engineer and pioneer in the field of flavor science, had just been recruited by the Office of Strategic Services (OSS). The new government agency, a precursor to the CIA, was devising unusual new methods of waging war—everything from grenades disguised as lumps of coal to covert missions to “feminize” Hitler by lacing his food with estrogen. In the final years of World War II, it was embarking on a project requiring someone who understood the chemistry underlying the world’s foulest odors. Crocker, later dubbed the Man with the Million-Dollar Beak by the Saturday Evening Post, clearly had the best nose for the job.

During World War I, long before the OSS came calling, Private Ernest Crocker was one of 1,700 chemists in Washington, DC, who worked to develop more effective poisonous gases for the military. The work involved experimenting with deadly gases as well as with harmless but stinky vapors sometimes deployed as odiferous red herrings to trick the enemy. Days in the lab left Crocker and his roommate, chemist Lloyd Henderson, smelling so awful that they often abandoned their room and slept in a nearby park, whiling the nights away discussing why smell was so hard to study.

One reason, the pair decided, was that unlike plants or bacteria, smells had no formal scientific classification system. In the mid-1920s, when both found themselves working at Arthur D. Little, they landed funding from the perfume industry and began building what they thought was the world’s first such scheme. (They would later learn that the German psychologist Hans Henning had already beaten them to it.)

Crocker and Henderson started searching for “primary” foundational scents found in any smell detectable with the human nose. They chose four—fragrant notes found in flowery and fruity smells, acid notes that characterize sour and acrid odors, burnt notes, and caprylic notes, which the team defined as “the unpleasant type of odor associated with the billy goat.” Skunky smells and animal odors—think wet dog—have strong caprylic notes.

Crocker and Henderson could distinguish eight intensities of each element, and after carefully sniffing 525 materials ranging from sandalwood to rancid fat, they devised a classification system that would assign each scent a unique four-digit number—each digit representing a different element ranked from 0 through 8 according to intensity. Freshly roasted coffee, a smell with strong fragrant and burnt elements and weak caprylic notes, was coded as 7683, while hay, which is largely defined by its fragrant and caprylic notes, was coded as 5114.

The Crocker-Henderson method proved too subjective to be reliable, but in the thick of World War II, it attracted the attention of Stanley Lovell, head of research and development for the OSS. Crocker was recruited in 1943 to design one of its most creative weapons—a military-grade stink bomb that could be distributed to resistance groups and used to make its target “a source of derision or contempt,” according to declassified OSS files.

Those documents reveal that the researchers were asked to create a cocktail of noxious odors that could be inflicted on an individual or used to clear out Axis meeting spaces and storage facilities. The substance should be persistent, “produce unmistakable evidence of extreme personal uncleanliness,” and, ideally, induce nausea. But its real purpose was psychological—to destroy morale through embarrassment. The project—cheekily code-named “Who, Me?”—would require Crocker’s team to create a universally repulsive smell.

The British were already on the case. By the time Crocker was recruited, British intelligence had extensively researched the aromatic composition of excrement—one declassified document called “Facts About Feces” provides details right down to the chemical distinctions between alkaline excretions associated with meat-based diets and the “voluminous stools” produced by diets rich in milk. The Brits had also developed a concoction called “S Liquid” (S being short for “stench”), which contained skatole, a compound formed in the intestines that gives feces their aroma.

Crocker spent months testing combinations of the world’s most vile odors, and by March 1944 he had settled on a mixture of skatole, amyl mercaptan, and butyric, valeric, and caproic acids that together assaulted the senses with smells of vomit, rancid butter, urine, rotten eggs, foot odor, and excrement. In late 1944, Crocker also developed a second formula to use against the Japanese. Concern that Japanese people might be accustomed to open sewers and the racist Western belief that they might even be immune to the stench of human waste led him to remove skatole and incorporate alpha ionone to add cadaverous notes.

Packaging presented a major hurdle. Technicians at Maryland Research Laboratories, where the original formula was tested, routinely found themselves covered in unwashable stench when samples went through handling trials. Much of 1944 was spent on package designs—ideas ranged from crushable glass capsules to tubes with break-off tips—but Crocker’s team finally figured out how to seal tubes by building a lip of rubber tubing into the cap. Samples passed the handling tests that autumn, and ultimately 600 units of Who, Me? were prepared for deployment.

The war ended before Who, Me? hit the battlefield, but Crocker went on to use his research on what turns our stomachs to do just the opposite. Called “the most prominent flavor scientist of his generation,” he spent the rest of his career studying the chemical and perceptual aspects of smell and flavor. Crocker’s work, which among other things included evaluating flavor conservation methods, manipulating natural flavors through controlled heat, and studying the psychological impact of tastes, ultimately helped establish sensory science and food technology as scientific fields. In recent years, research in those areas has produced such things as scentless cleaning products and odor-resistant clothing; at MIT, chemistry professor Tim Swager’s lab has invented carbon-nanotube-based sensors that can detect when meat and produce are past their prime.

So if Crocker’s nose didn’t defeat the Nazis, it did lead the way to a series of smaller sensory victories.