Alice Ball invented a chemical technique for converting chaulmoogra oil into an injectable, water-soluble form that became the first effective treatment for Hansen’s disease, commonly known as leprosy. Working at the University of Hawai’i in 1915, the 23-year-old chemist developed what came to be called the “Ball Method,” a process for isolating the ethyl esters of chaulmoogra oil’s active fatty acids so they could be absorbed by the body without the brutal side effects of swallowing the raw oil. Her work changed the treatment landscape for a disease that had condemned patients to lifelong isolation, yet Ball died at just 24 and went decades without proper credit for her achievement.
The Problem with Chaulmoogra Oil
For centuries, oil pressed from the seeds of the chaulmoogra tree (Hydnocarpus wightiana and related species) was one of the few substances believed to help people suffering from leprosy. Folk medicine traditions across South and Southeast Asia used it as a topical salve or oral remedy. By the early twentieth century, Western physicians had taken notice, and chaulmoogra oil was considered the best available treatment. But “best available” did not mean good. When patients drank the oil, it caused severe nausea and vomiting, making it almost impossible to keep down in therapeutic doses.1Leprosy Review. Lepra at one hundred years: A century of innovation and research
The side effects went far beyond an upset stomach. A study of nearly 2,818 patients treated with chaulmoogra oil found that over 70 percent experienced complaints directly or indirectly caused by the treatment. Kidney damage was rampant: at the start of treatment, about 30 percent of patients had abnormal protein (albumin) in their urine and 15 percent had urinary casts, indicators of kidney stress. After a year and a half of treatment, those figures climbed to 95 percent and 88 percent respectively. Deaths from tuberculosis and kidney disease were far more common among treated patients than untreated ones.2Mayo Clinic Proceedings. The Pharmacologic Action of Chaulmoogra Oil in the Treatment of Leprosy: A Summary of the Results of Nearly Two Years of Study The cure, in many cases, was nearly as dangerous as the disease.
Physicians tried injecting the oil directly, hoping to bypass the digestive tract. Leonard Rogers reported results from chaulmoogra injections as early as 1917.1Leprosy Review. Lepra at one hundred years: A century of innovation and research But raw chaulmoogra oil is thick and sticky. Injecting it caused painful abscesses and swelling at the injection site. The oil simply did not mix well with the body’s water-based fluids, which meant it pooled under the skin rather than dispersing into the bloodstream where it could actually fight the infection. The medical community needed someone to solve a chemistry problem: how to get chaulmoogra’s active ingredients into the body in a form it could actually use.
What the Ball Method Actually Did
Alice Ball’s insight was to chemically transform chaulmoogra oil into something the body could absorb. Chaulmoogra oil is unusual among plant oils because roughly 80 percent of its fatty acid content consists of cyclopentenyl fatty acids, ring-shaped molecules not commonly found in other natural oils.3Phytochemistry Letters. Chemical composition and antibacterial activity of chaulmoogra oil from Hydnocarpus wightiana: A detailed analysis of volatile and fatty acid fractions These fatty acids, particularly chaulmoogric acid and hydnocarpic acid, were the components that showed activity against the leprosy bacterium. But in their natural oil form, they were not water-soluble and could not be injected safely.
Ball developed a multi-step process to isolate individual fatty acids from the oil and then convert them into their ethyl ester derivatives. An ethyl ester is formed when a fatty acid reacts with ethanol under the right conditions, producing a new molecule that retains the original fatty acid’s disease-fighting properties but behaves differently in water and in the body. The resulting compounds were water-soluble, meaning they could dissolve into the body’s fluids after injection and be carried through the bloodstream to where the leprosy bacteria were active.4PubMed. Alice Augusta Ball: The African-American chemist who pioneered the first viable treatment for Hansen’s Disease
The practical difference was enormous. Instead of swallowing a thick, nauseating oil or enduring painful lumps under the skin from crude injections, patients could receive a simple shot that their bodies could actually process. The active compounds reached the bloodstream, circulated to infected tissues, and were gradually metabolized and cleared. Ball had essentially solved the drug-delivery problem that had plagued chaulmoogra treatment for decades.
Why Chaulmoogra Works Against Leprosy
Leprosy is caused by Mycobacterium leprae, a slow-growing bacterium that attacks the skin, nerves, and mucous membranes. What makes chaulmoogra’s unusual fatty acids effective against this pathogen comes down to those distinctive ring-shaped molecules. In laboratory and animal testing, chaulmoogric acid and its close relative dihydrochaulmoogric acid were shown to inhibit the multiplication of M. leprae when administered by injection. Palmitic acid, a common straight-chain fatty acid found in many foods, had no such effect, which confirmed that it was specifically the cyclopentenyl structure that gave chaulmoogra its antimicrobial punch.5PubMed. The activity of chaulmoogra acids against Mycobacterium leprae
The mechanism is thought to relate to how these ring-shaped fatty acids interact with the mycobacterial cell wall. Mycobacteria, including both M. leprae and its relative that causes tuberculosis, have unusually thick, waxy cell walls that make them resistant to many treatments. The cyclopentenyl fatty acids appear to disrupt the structure of this cell wall, interfering with the bacterium’s ability to grow and divide. Ball’s contribution was not discovering that chaulmoogra oil could fight leprosy; people had known that for centuries. What she figured out was how to deliver those active compounds in a form that actually reached the bacteria inside the body, in sufficient concentrations, without poisoning the patient in the process.
How Ball Lost Credit for Her Own Work
Alice Ball completed the core work on her method in 1915, while simultaneously serving as the first woman and first Black person to earn a master’s degree in chemistry from the University of Hawai’i. She was also the university’s first female chemistry instructor. But in late 1916, at just 24 years old, she died. Her exact cause of death remains a matter of historical debate, though exposure to chlorine gas during a laboratory demonstration may have been a contributing factor.
Ball died before she could publish her findings. Arthur Dean, the president of the College of Hawai’i (the precursor to the University of Hawai’i), continued her research and published the results without acknowledging her contribution. He referred to the injectable chaulmoogra preparation as the “Dean Method,” effectively erasing Ball from the story of her own discovery. Ball did not receive recognition for her work, and she was largely forgotten after her death.4PubMed. Alice Augusta Ball: The African-American chemist who pioneered the first viable treatment for Hansen’s Disease
It was Harry T. Hollmann, a physician at the Kalihi Hospital leprosy clinic who had originally recruited Ball for the chaulmoogra project, who pushed back. Hollmann published a paper in 1922 explicitly crediting Ball for the method, calling it the “Ball Method” and making clear that the chemical technique was hers. Without his intervention, it is possible her name would have been lost entirely. The episode reflects a pattern that was all too common in early twentieth-century American science, where the contributions of Black researchers and women were minimized or stolen outright, and where institutional power made it easy for senior figures to claim credit for junior colleagues’ work.
The Treatment in Practice
Once Ball’s method made injectable chaulmoogra available, it quickly became the standard treatment at the Kalihi Hospital in Honolulu and at leprosy settlements across Hawai’i, including the well-known colony at Kalaupapa on the island of Moloka’i. Patients who had been confined to these settlements for life, with no hope of release, suddenly had a treatment that could reduce their symptoms enough to be considered for discharge. For a disease that carried severe social stigma and often meant permanent separation from family, this was transformative.
The ethyl ester injections were not a perfect cure. Leprosy is a chronic infection, and treatment required repeated injections over months or years. Some patients experienced significant improvement, with skin lesions clearing and nerve damage stabilizing. Others responded less well. But compared to the alternatives available in the 1910s and 1920s, the Ball Method represented a genuine breakthrough: it was the first viable treatment for leprosy, and it changed the lives of millions worldwide who had been affected by the disease and the social isolation that accompanied it.4PubMed. Alice Augusta Ball: The African-American chemist who pioneered the first viable treatment for Hansen’s Disease The treatment continued in widespread use for nearly two decades after Ball’s death, a remarkable lifespan for any medical intervention of that era.
What Replaced the Ball Method
By the 1940s, a new class of drugs began to overtake chaulmoogra-based treatments. Diaminodiphenyl sulfone, known as DDS or dapsone, proved to be a more effective and convenient oral medication for leprosy. The transition from chaulmoogra oil to sulfone drugs represented a major shift in how leprosy was treated globally, with medical workers in places like Hong Kong and Taiwan helping to develop practices centered on mass administration of DDS.6Science, Technology, & Human Values. Curing Leprosy with DDS: Metamorphosis of Colonial Medicine into Global Health
Dapsone had clear advantages. It could be taken as a pill, which was far simpler than a regimen of regular injections. It was cheaper to produce and easier to distribute, which mattered enormously in the tropical and subtropical regions where leprosy was most prevalent. And it was more reliably effective across different patients. Eventually, the World Health Organization introduced multi-drug therapy in the 1980s, combining dapsone with rifampicin and clofazimine, which remains the standard treatment today. This combination approach dramatically reduced the global burden of leprosy, from millions of active cases to fewer than 200,000 new diagnoses annually.
The arrival of sulfone drugs does not diminish what Ball accomplished. She solved the problem that existed in her time with the tools available to her, and her solution worked well enough to remain the primary treatment for a generation. The fact that better drugs eventually came along is simply how medicine progresses. Every effective treatment eventually gives way to a more effective one.
Who Alice Ball Was
Alice Augusta Ball was born in Seattle, Washington, in 1892, into a family with connections to both photography and higher education. Her grandfather, James Ball Sr., was a well-known photographer, and her family valued intellectual achievement. Ball excelled academically from an early age, earning a bachelor’s degree in pharmaceutical chemistry and a second bachelor’s degree in the science of pharmacy from the University of Washington before moving to Hawai’i to pursue her master’s degree. She completed her master’s thesis on the chemical properties of kava root, the traditional Pacific Island plant used to make a calming drink. That thesis impressed the faculty enough that she was offered both a teaching position and the chaulmoogra oil research project.
Ball was 23 when she developed the method that would define her legacy, working at the intersection of organic chemistry and pharmacology at a time when Black women faced enormous barriers in science. The University of Hawai’i, located far from the segregated mainland United States, offered a somewhat more open environment, but Ball’s accomplishments were still extraordinary by any standard. She was the youngest person, and the first Black person, to receive a master’s degree in chemistry from the university. She was simultaneously teaching undergraduates while conducting her own research, a workload that would be demanding for anyone.
Her death at 24 cut short what could have been a remarkable career. Ball never saw the widespread adoption of her method, never published the definitive account of her work, and never had the chance to defend her contribution when Arthur Dean claimed it as his own. For decades, she existed only in footnotes and the memories of a few colleagues who knew the real story.
Belated Recognition
The recovery of Alice Ball’s story is largely a product of the late twentieth and early twenty-first centuries. In 2000, the University of Hawai’i placed a bronze plaque near a chaulmoogra tree on campus, honoring her contribution. The former lieutenant governor of Hawai’i, Mazie Hirono (later a U.S. senator), declared February 29 “Alice Ball Day” in the state. Scholars and historians have worked to piece together the details of her life and career, and she has become a prominent figure in efforts to recognize overlooked contributors to science.
Ball’s story resonates well beyond the specific chemistry she performed. It raises questions about how credit is assigned in science, who gets remembered and who gets forgotten, and how institutional power can shape the historical record. Dean’s appropriation of Ball’s work was possible in part because she was a young, Black woman who had died before she could establish her professional reputation. Had she been a senior white male professor, it is hard to imagine her contribution would have been so easily erased. The fact that it took the better part of a century for the scientific community to fully restore her credit speaks to how durable these erasures can be once they take hold.
Chaulmoogra Oil in Modern Research
Though dapsone-based multi-drug therapy replaced chaulmoogra oil as a leprosy treatment decades ago, the oil itself has not entirely vanished from scientific interest. Modern chemical analysis has confirmed and expanded on what early twentieth-century chemists like Ball understood about its composition. Gas chromatography-mass spectrometry analysis of chaulmoogra oil from Hydnocarpus wightiana has shown that cyclopentenyl fatty acids make up about 80 percent of the fatty acid fraction, with additional volatile compounds present in smaller amounts.3Phytochemistry Letters. Chemical composition and antibacterial activity of chaulmoogra oil from Hydnocarpus wightiana: A detailed analysis of volatile and fatty acid fractions Researchers continue to investigate the oil’s broader antibacterial properties, looking at whether its unique fatty acid profile has applications beyond mycobacterial infections.
There is something fitting about this continued research. Ball worked with crude extraction methods and the analytical tools available in 1915, yet she correctly identified and isolated the active components that modern instruments have confirmed were the right targets. The cyclopentenyl fatty acids she turned into injectable ethyl esters are the same molecules that today’s mass spectrometers flag as the dominant bioactive fraction of the oil. She got the chemistry right, with a fraction of the technology that would later be available to verify it. For a 23-year-old working in a small university lab in Honolulu, that remains an impressive scientific achievement by any measure.