Agnes Pockels Find Wonder While Washing Dishes and Invents Surface Science

Agnes Pockels, linocut, 11" x 14" on Japanese paper, by Ele Willoughby, 2026

The seventh prompt for #PrinterSolstice2026 is division, and I have decided to focus on the dividing line or interface, and the self-taught scientist who pioneered surface science. 

When Agnes Pockels (1862-1935) was 18, she did not get the chance to go to university and study physics like her brother Friedrich, who became a professor of theoretical physics and discovered the Pockels effect studying optics and electromagnetism. She took her "passionate interest for natural science" to those household chores she was allowed to pursue, and applied her analytic mind and careful observation to what she saw even in greasy dishwater. She became fascinated with how soap behaves on the surface of the water, and especially in the effect of impurities. She began performing experiments as an amateur chemist. In so doing, she pioneered the entire field of surface science describing physical properties of liquids and solids at interfaces, gained international recognition, published a series of peer-reviewed papers and earned an honorary doctoral degree from Braunschweig University, Germany. Performing kitchen-table research, she developed a surface film balance technique to study soap and surfactants at the air-liquid interfaces and defined the Pockels point, the minimum area a single molecule can occupy in a monomolecular film.

Agnes Pockels' first paper 'Surface Tension'
published in Nature in 1891, complete
with Lord Rayleigh's introduction.

Born in Venice in 1862, when it was part of the Kingdom of Lombardy-Venetia, Agnes' father Theodor served in the Austrian army. Malaria was an ever-present risk in the region and struck the family. When Theodor fell ill in 1871, he retired and moved the family, his wife Alwine, daughter Agnes and son Friedrich, to Brunswick, in the newly formed German Empire. Agnes was interested in science, and attended the Municipal High School for Girls. Though she would have loved to pursue higher education in science, and especially in physics, women were not admitted to German universities (with a very few notable exceptions). So, she studied science at home, while caring for her parents for three decades, as expected for an unmarried daughter. When her younger brother Friedrich went to study physics at the University of Göttingen, he would share his textbooks with her. Later, he would supply her with research in the academic literature to help her pursue her own self-taught studies. When the universities finally began admitting women, Agnes followed her father's wishes and refrained from attending so she could continue keep house and to care for her sick parents.

She began experiments when she was 18, and by age 20 in 1882, she had devised a slide through for making quantitative measurements of soapy water and other materials. Her water-filled through was 70 cm long, 5 cm wide and 2 cm deep and she laid a metal strip (about 1.5 cm wide) on the water, across the width of the through, so she could divide the surface into two parts. A lengthwise ruler along the through allowed her to precisely measure the surface area of both sides as the strip was moved along the length of the through. Building on the plate method of Ludwig Wilhelmy, she devised a simple but clever means of measuring surface tension in either area with a ceramic button (6 mm in diameter) placed on the surface. She would raise the button with an apothecary's balance or weighing scale to measure the force required to lift it from the water. She could then compare the force required to lift her button from pure water, or water with various added substances and impurities. Using her through, she investigated surface forces of monomolecular films, emulsions, solutions and the effect of impurities on physical properties and she came to understand surfactancy, the property of a chemical compound to decrease surface tension at an interface between different materials (at least one of which is a fluid).  She found that small amounts of impurities could have a large impact on surface tension. 

Agnes Pockels in 1885

Her through influenced future experimentalists in colloidal and surface science who employ the modern Langmuir-Blodgett through, an improved apparatus based on her work, still in use today. When Irving Langmuir won the 1932 Nobel Prize in Chemistry for his work in the surface chemistry of oil films, he was building on the 18 year old autodidact Agnes Pockels' experiments with a button and thin tray, performed in her kitchen (not that he bothered to mention this in his Nobel lecture). Her sister-in law, Elisabeth Pockels wrote, "every day, millions of housewives were unhappy to see greasy dish water and just wanted to get rid of it, but it inspired this very person to make observations and finally also work on scientific treatises." She made her meticulous investigations for a full decade without any communication or collaboration with the world of academic science. She had tried writing to physicists at the University of Göttingen about her work but received no reply. Then in 1890, her brother sent her a paper on surface phenomena by renown physicist Lord Rayleigh.  With her brother's encouragement, she wrote Rayleigh a modest, 12 page letter, including all her results. She explained that she had been unable to publish her results in any scientific journal and she gave him her permission to use her results if they were at all useful. Rayleigh did not speak German, but luckily, his wife Evelyn could translate the letter for him. He instantly recognized the importance of Agnes' work and to his credit he sent them to Nature, putting the weight of his reputation behind supporting the work of an unknown amateur, writing, "I shall be obliged if you can find space for the accompanying translation of an interesting letter which I have received from a German lady, who with very homely appliances has arrived at valuable results regarding the behaviour of contaminated water surfaces. The earlier part of Miss Pickles' letter covers nearly the same ground as some of my own recent work, and the main harmonises with it. The later sections seem to me very suggestive, raising if they do not fully answer, many important questions. I hope soon to find opportunity for repeating some of Miss Pockels' experiments." Nature published Ages' letter with Rayleigh's cover letter. This paper, 'Surface Tension' is considered a landmark in the history of surface chemistry.

Seeing her research published encouraged her to continue her experiments, and her correspondence with Rayleigh. She wrote to him about the paramount importance of cleanliness in these experiments and her recognition of how contamination had hampered her previous efforts. Even dust could hinder reproducibility. To study monolayer films, she developed a procedure for the deposition of the compound of interest as a solution in benzene on the surface of the water in her trough and she was able to measure layer thickness at 13Å (an Angstrom is a billionth of a metre, roughly the size of a single atom). She published her second paper, with Rayleigh's help, in Nature in 1892. She went on to study forces on monomolecular films, the calming effect various oils can have on water, various liquids and their adhesion on glass and the surface tension of emulsions and solutions, other surface phenomena like capillary and contact angles, publishing her results in scientific journals including Nature, Wissenschaftliche Rundschau, Annalen der Physik, and Science.  She was invited to give public lectures by German universities.  She published subjects beyond surface science, including her translation of Georg Howard Darwin's 'The Tides and Kindred Phenomena in the Solar System' and a philosophy paper in Annalen der Naturaphilosophie. 

German scientists finally took notice. At the Physikalische Institut of Techniche Hochschile Brauschweig (the Physical Institute of the Technical University Brauschweig), crystal physicist Woldemar Voigt (1850-1919) offered her lab facilities, so over the next decade, she squeezed in further research there around her responsibilities at home. 

Soaps are surfactants made of molecules which have a "water loving" hydrophilic head and a water-repelling hydrophobic tail which is insoluble in water and tends to sit on its surface. Using her sliding through, Agnes found the tiny addition of surfactants had a small impact on surface tension until the slider passed a certain point, where tension would suddenly increase. She plotted surface tension versus slider position, showing the compression isotherm. She realized that the point the compression isotherm abruptly changed was when the continuous film of surfactant was a single molecule thick. With further experimentation she found that the threshold point is the same for a variety of surfactants. Knowing the volume of surfactant soap and the surface area covered by the film, she was able to calculate the surface area of the water occupied by a single molecule to be 20 square Angstroms, now known as the Pockels Point.

Early in the new century, in 1902, her parents' worsening health interrupted her work at the university and she became their full-time carer. Her father died in 1906, her brother died in 1913 and her mother died in 1914. She herself was in quite poor health and she needed to have a stay in a sanitarium. Then during the first world war, she lost contact with the scientific community. Germany was isolated and she was unable to access the foreign scientific literature. Her health and eyesight deteriorated. She had invested wisely and was more financially insulated than other Germans from the post-war financial chaos. She felt the responsibility to protect those around her from the threat of hunger and homelessness and she stopped carrying out her experiments. She published the last of her 14 papers, reviewing her classic work, in 1926. She spent her later years travelling in Europe and as the devoted Auntie Agnes to her brother's children. She finally received public recognition for her work, winning the Laura R. Leonard Prize of the Colloid Society in 1931. In 1932, Techniche Hochschile Brauschweig granted her an honorary doctorate in engineering. She was the first woman to receive such an award. Legendary German colloid chemist Wolfgang Ostwald published her biography on her 70th birthday in 1832. Her sister-in-law Elisabeth Pockels also wrote a biography of Agnes, focusing on her personal life. Since 1993 the university has granted the Agnes Pockels Medal to people who have made outstanding contributions to the development of the university, promoting research and teaching, particularly by women. In 2002 Techniche Hochschile Brauschweig established the Agnes Pockels Laboratory to foster chemical education and aid chemistry teachers, focusing on children under 10, especially girls.

Despite her limited access to education Agnes Pockels found wonder in a mundane tub of dishwater, and launched an entirely new field of science.

References

Agnes Pockels, Wikipedia, accessed January, 2026

DeBakcsy, Dale. How a Kitchen Experiment Spawned a New Science: The Surface Physics of Agnes Pockels. The Women in Science Archive. October 16, 2023.

Derrick, M. Elizabeth. Agnes Pockels, 1862-1935, Journal of Chemical Education, vol. 59, no, 12, pp. 1030-1031, December 1982

Gratzer, Walter (ed.). A Beside Nature - Genius and Eccentricity in Science 1869-1953. W.H. Freeman and Company, New York. pp. 88. 1999.

Kruse, Andrea and Sonja M. Schwarzl. "Zum Beispiel Agnes Pockels," Nachrichten aus der Chemie, 06, 2002, translated as "Who was Agnes Pockels - Agnes Pockels - Housewife and Chemist", Braunschweig Technical University, accessed January, 2026.

RAYLEIGH Surface Tension. Nature 43, 437–439 (1891). https://doi.org/10.1038/043437c0

Marie Meudrac, where the transition from alchemy to chemistry meets medicine, cooking and cosmetics: chemistry by a woman for women

Marie Meurdrac, linocut, 9.25" x 12.5" by Ele Willoughby, 2025

This is my hand-printed linocut portrait of Marie Meurdrac (c. 1610-1680), one of the first chemistry textbook authors and the first woman to publish a book on early chemistry. Working right at the transition between alchemy and chemistry, in 1666 she published 'La Chymie charitable & facile, en faveur des dames' (Charitable and easy chemistry for ladies). I selected her for the #printerSolstice2425 prompt sodium, as for her, salt, "the father of generation" was the first of the 3 elements, salt, sulphur and mercury, from which all materials were made. 

We do not know a great deal about her life for certain. Born to a land-owning family, in Mandres-les-Roses, now a suburb of Paris, to Vincent Meurdrac or Meurdrat, a notary, and Elisabeth Dove.  Her younger sister Catherine, became the author and memoirist with the nom de plume Madame de la Guette.  She married a military man. Her sister recorded his name as Monsieur de Vibrac, captain du château de Grosbois, where she moved after her marriage. He was commander of Charles de Valois, Duke of Angoulême (illegitimate son of Charles IX of France)'s guard unit. However the Abbot Sanson recorded that she married Guillaume de Brisset; but this discrepancy might be explained if Guillaume de Brisset succeeded his father Monsieur de Vibrac to both the fiefdom of Vibrac and the captaincy.  In any account, living there, she became good friends with Countess de Guiche. She taught herself chemistry following the works and experiments of her contemporaries and reading books on chemistry and alchemy. She had her own lab where she tested all her remedies and recipes. She dared to write a handbook of practical chemistry, which helped popularize the subject throughout Europe, at a time when the very idea of scholarly women was ridiculed in France. The  woman question ("la querelle des femmes")- or rather the question of whether women should be educated at all was widely debated. The book is dedicated to the countess; Meurdrac had access to a high temperature furnace which required permission of the king which she might have got thanks to the countess. 

Chemistry had long been practiced by women in cooking in the kitchen, in making household remedies and cosmetics, but as sciences became formalized it became a man's world. Meurdrac had been keeping notes of all her experiments so as not to forget her results when she realized she had enough for a book as complete or more so than other available chemistry handbooks. The word “chymie” comes from 16th century Swiss doctor Paracelsus, and following in his tradition, she believed that matter is made of various quantities of 3 elements: salt, mercury, and sulphur, but unlike previous alchemist authors (including those she cites like Raymond Lull and Basil Valentine) her writing is clear and unpretentious rather than obscure. She wants to expose what alchemists would keep a secret for the select few. She omits the astrological conditions so come in alchemical recipes. 

The Preface from Marie Meurdrac's  'La Chymie charitable & facile, en faveur des dames' complete with her argument "les Esprits n'ont point de sexe"

She wrote about her uncertainty in daring to publish as a woman, concerned that it might be above her station and knowing that men scorn the products of women's minds but concludes that but minds "have no sex and that if the minds of women were cultivated like those of men, and that if as much time and energy were used to instruct the minds of the former, they would equal those of the latter.” Her words, "les Esprits n'ont point de sexe" appear in my print, as in her book. Knowing that bourgeois or even aristocratic women were denied formal scientific education in universities, she wanted to provide accessible chemistry, botany, pharmacology, medicine, as well as in cosmetics knowledge and hands-on training to women. As women could not legally practice medicine, providing free healing services and lessons was a sort of loophole for her, hence the word "charitable" in her title.  She covered items such as lab techniques, properties of medicines, and cosmetics. She also had a table of weights and 106 alchemical symbols that were used in medicine at the time. The jars behind are marked with these symbols. She presents ingredients as "principles" rather than materials, in the manor of the alchemists and describes methods used both by alchemists and early chemists such as distillation, sublimation, rectification, calcination, cohobation and so forth, with specific vessels and fires to be used. She includes recipes which could be found in contemporary chemistry texts such as for Flowers of Bezoin, or Salt of Saturn. Following Paracelsus she writes about plants in medicine, as they believed them superior to other matter, created prior to animals according to Genesis and having survived the great flood. She was wary of using metals in medicine, viewing such treatment as more aggressive. She brought her knowledge to a wide audience, empowering women to make their own remedies and cosmetics safely, for instance, correctly warning of the dangers of using poisonous mercury sublimate to whiten skin as was done at the time. 

She is surrounded with books, tools, supplies and plants she would have used including scales, glassware, tongs, and a furnace, inspired by the frontispiece in one of the several editions of her book. The plants are rosemary, which she describes as a universal antidote to all sorts of illnesses, and tansy, used to facilitate childbirth. The book was popular for more than 50 years, with five editions in France, six in Germany, and one in Italy. She encouraged her readers to follow her lead and use their skills to freely treat the poor. Recognizing the cost of materials and tools she offers her readers some more accessible alternative suggestions and offers advice on finding the more rare ingredients. She even offers to answer readers' questions or even make demonstrations in person. Writing about chemistry for women, when it was claimed by men for men, was transgressive, and she defends her ability to do so with her strong feminist argument. She made hands-on training in chemistry, botany, pharmacology, and medicine, as well as in cosmetics accessible to generations of women. 

References

Bulletin du bibliophile, Volume 24, Techner, 1859. pp. 252-253

Fiendstein, Sandy. Experience, Authority and Alchemy of Language: Margaret Cavendish and Marie Meurdrac Respond to the Art. Early Modern Women, Volume 15, Number 2, Spring 2021, pp. 133-142 (Article) Published by Arizona Center for Medieval and Renaissance Studies. DOI: https://doi.org/10.1353/emw.2021.0028

Fiendstein, Sandy. La Chymie for Women: Engaging Chemistry's Bodies. Early Modern Women: An Interdisciplinary Journal, vol 4, 2009, pp. 223-234.

Findlay, Sam. 'Mind has no sex': The story of Marie Meurdrac, First Lady of Chemistry, ARC Centre of Excellence for Electromaterials Science, March 10, 2015.

Gordon, Robin L. 2015. Marie Meurdrac. Women Alchemists: Stories and  Reflections on their Place in History, Psyche and Science. accessed, February, 2025

Marie Meudrac - La chymie pour les femmes, YouTube video by Sur les épaules des géantes, February 3, 2021

Marie Meudrac, Wikipedia, accessed February 2025 (both English and French versions)

Meurdrac, Marie.  La chymie charitable & facile, en faveur des dames : 1666, Paris, CNRS, 1999 octobre 1999(réimpr. présentée et annotée par Jean Jacques) (1^re éd. 1666), 249 p. (ISBN 2-271-05726-4).

Rayner-Canham, Marelene F.; Rayner-Canham, Marelene; Rayner-Canham, Geoffrey (2001). Women in Chemistry: Their Changing Roles from Alchemical Times to the Mid-twentieth Century. Chemical Heritage Foundation. pp. 4–5. ISBN 9780941901277.

Claudine Picardet: chemist, mineralogist, and scientific translator at the chemical revolution

Claudine Picardet, linocut print, 9.25" x 12.5" by Ele Willoughby, 2025

For the PrinterSolstice prompt oxygen I made a portrait of a woman who was right there in the thick of things when the element oxygen was becoming understood. This is my hand-printed linocut portrait of Claudine Picardet (née Poullet, later Guyton de Morveau, 1735-1820). She was at the centre of things, making experiments in chemistry, mineralogy, recording meteorologic data and perhaps most importantly, translating the latest science from Swedish, English, German, Italian and possibly Latin to French in the height of the chemical revolution.

Claudine Poullet was the eldest daughter of a royal notary, François Poulet de Champlevey, and she married barrister and member of the Académie royale des sciences, arts, et belles-lettres de Dijon, Claude Picardet in 1755. His membership in the Académie was Claudine’s entry into the high society scientific bourgeoisie. She attended lectures and demonstrations and became involved as a scientist, translator and host of her own salon. When she began her career she signed her translations and annotated textbooks as "Mme P*** de Dijon.” The couple had a son died at 19 in 1776. Her husband died in 1796, and she moved to Paris where she married her longtime scientific collaborator and friend Louis-Bernard Guyton de Morveau, deputy of the Council of five hundred and director and chemistry professor at the École Polytechnic. She continued her work and hosting scientific salons in Paris, where she was known as the Baroness Guyton-Morveau during Napoleon’s reign. 

Her extensive translation work was part of the Bureau de traduction de Dijon headed by Guyton de Morveau, which required her to maintain extensive contacts abroad, be conversant with the latest science, be polylingual and even to perform laboratory experiments and examinations of mineralogical specimens to confirm the results in texts she translated. She produced books, papers and manuscripts circulated amongst French scientists. The other half dozen members were all male academics; none were as prolific, or translated from as many languages nor published in the Annales de Chimie, like her. Established by Guyton de Morveau, Antoine Lavoisier, Claude Louis Berthollet in 1789, the Annales de Chimie paid translators as authors. She appears to eventually directed the team of translators. Claude-Nicolas Amanton wrote a misogynistic obituary crediting her work to her second husband, but this is contradicted by the evidence. She also was a prominent contributor, including works like her translation of John Hill’s Spatogenesia: the Origin and Nature of Spar; its Qualities and Uses (1772) to Jean-André Mongez’s Journal de physique.

She published the first translated volume of the chemical essays of Swedish chemist Carl Wilhelm Scheele, who was one of the discoverers of oxygen, from Swedish and German into French, collected as Mémoires de chymie de M. C. W. Scheele; She was the person who brought Scheele’s work to oxygen to the attention of scientists in France. She translated Abraham Gottlob Werner’s 1774 mineralogy textbook into French, expanding and annotating the original to the degree that her Traité des caractères extérieurs des fossiles, traduit de l'allemand de M. A. G. Werner, 1790 is considered a new edition of the book. She likely contributed substantially tho the translation of Torbern Olaf Bergman’s six-volume Opuscula physica et chemica (Latin, 1779–1790), usually attributed to Guyton de Morveau. She also translated Richard Kirwan’s papers and may have contributed to Marie-Anne Paulze Lavoisier’s 1787 translation of his Essay on Phlogiston. Along with all the works in chemistry and mineralogy, she translated some meteorology and astronomy like "Observationes astron. annis 1781, 82, 83 institutæ in observatorio regio Havniensi" (1784), reporting the astronomical observations of the longitude of the Mars knot, made in December 1783 by Thomas Bugge. She attended Guyton de Morveau’s chemistry lectures and studied the mineral collection of the Dijon Academy. She even invented some French scientific terms to capture Werner’s neologisms. 

From 1786 to 1787, Guyton de Morveau, Antoine Lavoisier, Claude-Louis Bethollet and Antoine-François Fourcroy met almost daily while they worked to modernize chemical nomenclature, creating the definitive names still used in inorganic chemistry today and writing “Méthode de nomenclature chimique.” This included rules like simple substances should have simple names like hydrogen and oxygen and compounds should have compound names designating their parts, like sodium chloride. A 19th century painting of the authors notably includes both Claudine Picardet, holding a book to indicate her roll as translator and Mme Lavoisier. They were integrated in this work and deserve to be remembered for their roles.

Together with her second husband, Claudine Picardet established Dijon internationally as a scientific centre. Her translation work occurred at a vital moment in the chemical revolution, and she was recognized for the importance of her work during her day; we should remember her today.

References

Antonelli, Francesca. Madame Lavoisier and the Others: Women in Marie-Anne Paulze-Lavoisier’s Network (1771-1836). Notes Rec. (2023) 77, 283–302 doi:10.1098/rsnr.2021.0074 Published online 13 July 2022 

Ashworth Jr., William B., Scientist of the Day - Claudine Picardet, Linda Hall Library, August 7, 2018

Claudine Picardet, Wikipedia, accessed January, 2025

Kahr, Bart. Gender and the Library of Mineralogy. Crystals 2022, 12(3), 333; https://doi.org/10.3390/cryst12030333

La femme savante de Dijon - Claudine Picardet - Mini bio 42, posted by Sur les épaules de géantes, YouTube video, watched January, 2025

Dorothy Crowfoot Hodgkin, chemist, crystallographer, Nobel laureate, mother, arthritis patient, peace and disarmament activist

Dorothy Crowfoot Hodgkin, linocut print, 11" x 14", by Ele Willoughby, 2025

The next prompt for PrinterSolstice is cobalt, an element animals including humans require for their metabolism, in the form of vitamin B12. So I made the portrait of English chemist and x-ray crystallographer Dorothy Mary Crowfoot Hodgkin (née Crowfoot, 1910-1994) won the Nobel Prize in chemistry for her models of biomolecules like penicillin, vitamin B12 and insulin, which were essential to structural biology.

The eldest of four daughters of English parents who were in the colonial administration of North Africa and the Middle East, and later, archeologists, Dorothy was born in Cairo, Egypt. The family escaped the heat of the summers by returning to England. When Dorothy was 4, her mother left her and her sisters Joan (2) and Elizabeth (7 months) with her Crowfoot grandparents near Worthing and returned to her husband and life in Egypt. The girls grew up with grandparents in England with parental support from afar. Dorothy became interested in chemistry as early as 4 and interested in crystals by age 10; "captured for life by chemistry and crystals," she later wrote. Her mother, a proficient botanist, encouraged her interests. She found a dark rock when visiting her parents in north Africa and asked a family friend, soil scientist A.F. Joseph if she could analyse it; he gave her a surveyor's box of reagents and minerals to encourage her.  She and her sisters would use a portable mineral kit to analyse pebbles they found in the stream.  During WWI, Dorothy lost four uncles on her mother's side influencing her to become an ardent supporter of the League of Nation and later a peace and disarmament activist. Her parents moved to Sudan where her father was in charge of eduction and archeology until 1926. In 1921, she entered Sir John Leman Grammar School, one of two girls allowed to study chemistry rather than domestic science usually assigned to girls.  She had one extended trip to spend time with her parents in Khartoum when she was 13.  A distant cousin who was a chemist, Charles Harrington (later Sir Charles) recommended D.S. Parsons' 'Fundamentals of Biochemistry' to her at age 14. She set up a a small lab in her attic, using chemicals she got from the local pharmacist. On her 16th birthday her mother gave her W.H. Bragg's 'Concerning the Nature of Things' about x-ray crystallography, which used the scatter pattern of x-rays through crystals at different angles, recorded on photographic plates to image crystals and use mathematics to then deduce their structure from these patterns. As Latin, required for entry to Oxford, was not on her school curriculum, the headmaster personally tutored her so she was able to pass the entrance exam. 

Post-WWI her parents eventually returned to their habit of summering in England to spend time with their children and escape the heat while working abroad. After retiring from the Sudan Civil Service in 1926, her father took job as Director of the British School of Archeology in Jerusalem and her parents lived there until 1935.

Dorothy joined her parents at the archeological site Jerash (present day Jordan) and documented patterns of mosaics of several 5th to 6th century Byzantine era churches, taking a year to finish her drawing just as she entered Oxford to study chemistry. There she also performed chemical analyses of glass tesserae from these sites. Her precise and meticulous drawings are now housed at Yale. She so enjoyed field archeology she considered switching her field of study. Her attention to detail in documenting patterns would later serve her well as a chemist. She graduated Oxford with a first class degree in chemistry in 1932.

She entered the PhD programme at Cambridge later that year studying with John Desmond Bernal and became interested in the use of x-ray crystallography to study the structure of proteins. She worked with Bernal on the first application of the method to image a biomolecule, pepsin. Previously, the method had only been used for inorganic crystals. Bernal believed in equal opportunities for women in chemistry and helped make x-ray crystallography one of the few fields with significant representation from women scientists. He followed in the example of William Bragg himself, who had 11 women amongst his 18 students. In 1933 she was awarded a research fellowship at Somerville College and returned to Oxford in 1934  to teach with her own lab equipment. She missed the day Bernal made the first photo of an x-ray of a protein crystal for health reasons. She was only 24 when she began experiencing pain in her hand which was diagnosed as chronic rheumatoid arthritis. She went to a clinic in Bruton for thermal baths and gold treatments before returning to work. The disease caused her hands to swell and become distorted; she had to add a special lever to the allow her to continue to use the main switch on the x-ray equipment. The disease is progressive and caused increasingly debilitating pain, problems and deformities in her hands and feet. She was appointed the college's first fellow and tutor in chemistry in 1936, a roll she held until 1977. She earned her PhD in 1937 on the x-ray crystallography and chemistry of sterols. In 1945 with C.H. Carlisle, she published the first structure of a steroid, chloresterol iodide. From 1941 through 45, she worked with colleagues including Barbara Low, on solving the structure of penicillin. She made her calculations manually with a set of specially printed paper strips and with her team plotted 108,00 points in the molecule to make two-dimensional contours of electron densities. With help from her sister, she drew the contour sheets on perspex so these 2D slices could be stacked to visualize the molecule in three dimensions. Only then could she make the traditional ball and stick model (like I have shown in my portrait); she surrounded hers with 2D contour plots of electron density. Country to scientific opinion, they found that penicillin contained a β-lactam ring. She was doing all this intense work while Thomas was teaching in Newcastle; she had to send him a telegram to alert him the arrival of their second child was imminent. The research was characterized as a wartime secret. She sent Thomas a postcard, 'Think we really have found out something for certain about P. Am extremely cheerful.' They completed the work on VE day in 1945. She became a Fellow of the Royal Society in 1947. They published their penicillin results in 1949; she bowed to social pressure at this point and added Hodgkin to her name, though she had up to this point published as Dorothy Crowfoot.

In 1948, Merck discovered vitamin B12, one of the most complex vitamins then known, and Hodgkin created some new crystals. Merck only published its refractive indices. When she realized it contained cobalt, she knew the almost completely unknown structure could be established with x-ray crystallography, but its size and largely unidentified atomic components would make it a challenge. Since the crystals were pleochroic, that is, they displayed different colours at different angles, she deduced the presence of a ring structure, confirmed by x-ray crystallography. Her 1954 published study was described by Nobel Laureate Lawrence Bragg as being as significant as "breaking the sound barrier." She published the final structure in 1955 and 56. 

In 1953, she, Sydney Brenner, Jack Dunitz, Leslie Orgel, and Beryl Oughton (later Rimmer), were the first people to drive from Oxford to Cambridge in two cars to see the model of the double helix of DNA built by James Watson and Francis Crick, informed by x-ray crystallography by Maurice Wilkins and Rosalind Franklin and their student Gosling. 

In 1957 the Royal Society awarded her the Royal Medal and she became a reader at Oxford, gaining a full, modern laboratory in 1958. She was appointed the Royal Society's Wolfs Research Professor in 1960 through 1970 which provided salary, research expenses and assistance and she was a fellow of Wolfson College, Oxford from 1977 to 1983. 

Insulin, illustrated by Dorothy Crowfoot Hodgkin. This drawing was presented to crystallographer Dr. Helen Megan who was organizing the Festival Pattern Group in Britain in 1951. Hodgkin refused a fee or to copyright an image found in nature. Megaw organized an exhibit of the wonders of scientific patterns applied in design as part of the Festival of Britain. I decided life is too short to try and make a relief print of a molecule this complex!

One of her most important and celebrated studies was the longest lasting. She first received a sample of insulin in 1934. The size and complexity of the molecule was too great to explore with x-ray crystallography at that time, but the importance of the hormone captured her imagination. She had paused this research to work on the structure of penicillin, which contains 17 atoms, and vitamin B12, which contains 181 atoms, but returned to it later. By 1969, 35 years later, she was finally able to work with an international team of young scientists to reveal the structure of insulin. Insulin contains 788 atoms! It's hard to overstate the size of the task and the sheer number of calculations involved. This work was instrumental in our ability to mass-produce insulin and treat diabetes and also to allow scientists to alter the structure of the molecule to create even better drug options. She remained active in collaborating on insulin production and drug development to better treat diabetes. 

Sample of insulin wallpaper design made for the Festival of Britain. This simplified and stylized insulin design inspired the blouse she's wearing in my portrait.

Soft-spoken and gentle but determined and hardworking, Hodgkin inspired her students, whom she encouraged to address her simply as Dorothy. Her most famous student moved on from chemistry to politics; conservative UK PM Margaret Thatcher (née Roberts), hung Hodgkin's portrait in her office, out of respect for her former tutor, the livelong Labour supporter, sometime Communist Party of Britain member and pacifist Hodgkin. Hodgkin's politics were greatly influenced by her mentor Bernal, an open and vocal communist and supporter of the Soviet regime until it invaded Hungary in 1956. She always called him "Sage" and they briefly had a relationship (unconventionally, Bernal had an open marriage) before she met Thomas Hodgkin. Thomas was teaching adult education classes in northern English mining and industrial communities, after resigning from the Colonial Office. Intermittently a member of the Communist Party, he later wrote several works on African politics and history and lectured at Balliol College, Oxford. The two married in 1937 and had three children, Luke (1938-2020), Elizabeth (1941), and Toby (1946). Thomas spent a much time in west Africa, supporting and chronicling emerging postcolonial states. A lifelong advocate for peace, Dorothy campaigned against nuclear arms and the Vietnam war. Because of Dorothy's political activities and her husband's communist party membership she was banned from entering the US in 1953, and subsequently not allowed in without CIA waiver. 

She was in Ghana, where her husband was an advisor to president in 1964 when she learned she had been awarded the Nobel Prize for Chemistry her work on the structure of biomolecules. She served as President of the International Union of Crystallography, an organization she helped found, from 1972 to 1975 and worked to foster international collaboration. She worked to include Chinese and Soviet scientists through the Cold War. In 1976 she won the prestigious Copley Medal, the first woman to do so (the second wasn't until Jocelyn Bell Burnell in 2021). Concerned about social inequities and preventing war and in 1976 she became the longest-serving president of the international Pugwash Conference on Science and World Affairs, which brings scientists and public figures to work together to reduce the risk of armed conflict and seek solutions to global security threats. She stepped down in 1988 after the signing of the Intermediate-Range Nuclear Forces Treaty ban on short and long-range nuclear weapons. She accepted the Lenin Peace Prize from the Soviet government in 1987 for her peace and disarmament work. Fellow chemist, peace activist and Nobel laureate Linus Pauling had recommended her for the award.

In later years she spent a great deal of time in a wheelchair because of the progress of the rheumatoid arthritis, but she was able to remain an active scientist. She skipped the 1987 Congress of the International Union of Crystallography in Australia, but attended the 1993 Congress in Beijing. She died by stroke in 1994 in her husband's village of Ilmington. 

The Royal Society now awards the Dorothy Hodgkin Award in her honour to outstanding early career scientists requiring flexible work due to caring or health reasons. The Council offices in Hackney, university buildings at the universities of York, Bristol and Keele and the science block at her old school Sir John Leman High School are named in her honour. Oxford International Women's Festival presents the annual Dorothy Hodgkin Memorial Lecture in her honour.

Her work helped in the rapid production of penicillin, considered a miracle drug at the time, mapping vitamin B12 helped the fight against pernicious anemia and her structure of insulin greatly improved our ability to treat diabetes. She left her mark on science and society both.

References,

All or Nothing,  Back From the Dead exhibit website from The Museum of the History of Science, 2021

Alman, Margaret. Art in the Atoms: Chemist Dorothy Crowfoot Hodgkin, blog post, February 3, 2010.

Cole, Rupert. Happy Birthday Dorothy Hodgkin. Science Museum blog. May 11, 2018

Dorothy Crowfoot Hodgkin, Nobel Prize website, accessed January, 2025

Dorothy Hodgkin, Wikipedia, accessed January, 2024

Hodgkin, Dorothy Mary Crowfoot, Jennifer Kamper, June Lindsey, Maureen F. Mackay, Jenny Pickworth, John H. Robertson, Clara Brink Shoemaker, J. G. White, R. J. Prosen and Kenneth N. Trueblood. “The structure of vitamin B12. I. An outline of the crystallographic investigation of vitamin B12.” Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences 242 (1957): 228 - 263.

Dmitri Mendeleev and the Periodic Table

Dmitri Mendeleev and the Periodic Table, linocut by Ele Willoughby, 2021

 

Here’s my Dmitri Mendeleev block print for the Printer Solstice prompt “elements”. I had meant to make his portrait for the 150th anniversary of the periodic table in 2019, but I didn’t get to it. I couldn’t quite figure out how to indicate what he did, in contrast to our modern periodic table. So many people would recognize the shape of the periodic table, from high school, even if they aren’t scientists who use it regularly. But Mendeleev didn’t publish his idea in a form that’s easy to recognize.

First, his table, as published in 1869, is rotated by 90° so it shows groups in rows rather than columns. Second, prior to the discovery of protons and neutrons, he listed and organized elements by atomic weight (now called atomic mass), rather than atomic number (or number of protons). Third, some of his data wasn’t great, so sometimes elements appeared to have the same mass, or were out of order or even were mixtures. He lists Didymium, which is actually a mixture of the elements Praseodymium & Neodymium.

Sometimes you need to think about visual ideas for a long time. Rather than including his notes, or published results as well as a modern periodic table, my idea is to show how much of the modern periodic table he was able to deduce despite limited data. The elements that were unknown or unmeasured are blank- something the viewer can rapidly understand. In several cases he predicted we would find the missing elements in groups (columns). Then, while an impressive amount of the elements known in 1869 are exactly in the right place, there are several which he placed in the wrong groups (due to inaccurate masses). I plan to print those he grouped incorrectly in a different colour. I think this can give an immediate sense of 3 categories: elements he’d figured out, elements he hadn’t quite got right yet, & gaps as of yet unfilled. And if you’ve studied chemistry you can get a sense of what he figured out & why. Even when he placed elements in the wrong group he usual correctly deduced similarities in behaviour found within groups (columns) which we eventually figured out could be explained by structure at an atomic scale.

You can see from Mendeleev's 1869 publication, he got most of the known elements in the right sequence and many in the correct groups. He understood there were connections in properties in adjacent elements and periodicities of properties of elements in the same groups (which he wrote as rows and we now show as columns). He also corrently inferred several as of yet undiscovered elements (see the question marks).

 Mendeleev was born in 1834, in the village of Verkhnie Aremzyani, near Tobolsk in Siberia, the youngest of child of a large family. He was likely the 17th (though 3 older siblings died as infants and there is some dispute among sources). His father was a school principal until he lost his sight and his job. His mother then restarted her family's abandoned glass factory to support the family. His father died and the glass factory was destroyed by fire. Despite economic hardship, 13 year old Mendeleev attended the Gynasium in Tobolsk. In 1849, his mother took him all the way to Moscow to try to get into the university, they were unsuccessful. The now poor Mendeleev family moved to Saint Petersburgh in 1850 so he could instead attend the Main Pedagogical Institute. He graduated, but contracted tuberculosis and went to the Crimean to recover, where he became a science master of the 1st Simferopol Gymnasium. When he was recovered in 1857 he returned to Saint Petersburg. He worked on  capillarity of liquids and the workings of the spectroscope, published the textbook 'Organic Chemistry' and won the Demidov Prize of the Petersburg Academy of Sciences. He married  Feozva Nikitichna Leshcheva (1862), professor at the Saint Petersburg Technological Institute (1864) and Saint Petersburg State University (1865). He got his doctorate on "On the Combinations of Water with Alcohol" in 1865 and got tenure in 1867. He wrote the definitive two-volume chemistry textbook of his day, 'Principles of Chemistry'. By 1871, he had made Saint Petersburgh and international recognized centre of chemical research.

While working on his textbook, he was struck by the periodicity of properties. There had been some earlier, not quite successful attempts to organize elements by properties (of which he was not aware). He claimed to see it in a dream,

"I saw in a dream a table where all elements fell into place as required. Awakening, I immediately wrote it down on a piece of paper, only in one place did a correction later seem necessary."
— Mendeleev, as quoted by Inostrantzev

He started with 9 elements, 3 groups of 3 types of properties, then added the other known elements around the core of the table. On 6 March 1869, he presented  ' The Dependence between the Properties of the Atomic Weights of the Elements' to the Russian Chemical Society, using both atomic weight (now called relative atomic mass) and valence. He published his table in a a Russian language journal.

Modern Periodic Table

He correctly noted that if you arrange elements by their atomic mass there show repeating periodic properties. (We now know that atomic number is more important than atomic mass, but they usual would give you the same sequence, especially for lighter elements). He noted similaries in elements of similar atomic weights (that is, adjacent on the table), and similaries in elements in regularly increasing increments (that is, now in the same columns). He realized the elements were ordered by their valencies. He noted that there are more lighter elements. He noted that atomic weight determines properties (though we would now say atomic number). He predicted as-of-yet undiscovered elements at gaps in his table. He inferred that some of the atomic weight data was not quite accurate because the placement in the table did not line up with properties. He noted that knowing the atomic weight could help you predict an element's properties.

He met Anna Ivanova Popova, and divorced his wife in order to marry her, but the divorce was not finalized until a month after his wedding; further the Russian Orthodox Church stipulated 7 years were required between marriages; so, he caused a scandal in 1882. This is likely why he was never admitted to the Russian Academy of Sciences. But he received international acclaim, including receiving the Davy Medal (1882) and Copley Medal (1905) from the Royal Society of London. He resigned from Saint Petersburg University in 1890. He was elected a Foreign Member of the Royal Society (ForMemRS) in 1892. In 1893 he was appointed director of the Bureau of Weights and Measures, for the remainder of his life. He died in at 72, in 1907, from influenza.

William Henry Perkin and the Discovery of Mauve

 

William Henry Perkin Discovers Mauve, linocut by Ele Willoughby, 2021

The next prompt for #printersolstice is "a well-made mistake" which prompted this tale of failure and serendipity.

This handprinted lino block print ‘William Henry Perkin Discovers Mauve’ is about how the British chemist and entrepreneur made the serendipitous discovery of the first synthetic organic dye: mauveine. William Henry Perkin (1838-1907) was only 18 and was washing up after trying and failing to synthesize quinine to treat malaria when he produce a bright mauve chemical from aniline and he recognized its potential as a dye. He set up a factory, revolutionizing fashion and launching the synthetic organic chemicals industry. The linocuts are 8” by 10” on ivory Japanese kozo (or mulberry) paper.

Perkin entered the Royal College of Chemistry in London in 1853 when he was only 15, studying with August Wilhelm von Hofmann. Hofmann hired him as his assistant in 1855 and had Perkin working on a series of experiments to try and synthesize quinine, used to treat malaria. During his Easter break in 1856, Perkin was performing some experiments to this end, in his makeshift lab in his own apartment. Hofmann thought allyl toluidine from coal tar could be oxidised with potassium bichromate to make quinine (which we now know cannot work). Perkin tried this method and got an unpromising brown precipitate. So instead he tried the method with another coal tar product, aniline, which produced a black sludge.... but left purple stains on the lab bench when he cleaned up with alcohol. Perkin was interested in painting and photography and had already been thinking about dyestuffs with his friend Arthur Church and his brother Thomas. They did not tell Hofmann. Perkin used a purified extract of the black sludge to colour samples of silk and sent them to a Scottish textile manufacturer. The results were so promising he decided to quit college, file for a patent and set up dye factory in Greenford Green, Middlesex. They named the dye mauveine.

Hofmann opposed his plan and feared the 18 year old lacked the experience to launch this enterprise, but he managed the logistics of securing ingredients reactive vessels and suitable mordants for dying. Then he tackled marketing the product: 'Perkin's mauve'.

His timing was perfect. Purple was a challenging colour to produce with natural pigments, many of which tended to fade. Considered a sign of royalty for centuries, 'Tyrian purple' was made from glandular mucus of certain molluscs; it was expensive and complicated to produce. Aided by Napoleon III's wife, the Empress Eugénie's choice of mauve fashion, as well as Queen Victoria favouring purple dresses, Perkin's mauve, the first mass-produced synthetic dye, became all the rage. In England they joked about 'mauve measles' and 'mauve mania'. Several of Hofmann's other students discovered other colours of synthetic dyes and an industry was born. Perkin was able to sell his business and retire from manufacturing at 36!

He then focused on research in organic chemistry. He published 90 papers in the Transactions of the Chemical Society, develipped the 'Perkin synthesis’ for unsaturated organic acids, did the first synthesis of coumarin, one of the first synthetic raw materials of perfume, synthesized cinnamic acid from benzaldehyde and developped a means of commercial production from anthracene of the brilliant red dye alizarin. He became a fellow of the Royal Society in 1866, received its Royal Medal in 1879 and Davy Medal in 1889, and was president of the Chemical Society and the Society for Chemical Industry. He had two sons by his first marriage to Jemima Lisset in 1859 (William Henry Jr and Arthur George). He remarried Alexandrina Mollwo after her death. They had a son (Frederick Mollwo) and four daughters (Helen, Mary, Lucie and Annie). They were a family of serious  musicians, who played together as a nine-piece chamber orchestra. Perkin had considered forming a professional string quarted with his brother and two sisters. His son William Perkin Jr was an excellent pianist. His son Arthur played flute with the family orchestra and later, first bassoon in a Yorkshire amateur orchestra. All three sons became chemists. William Henry Perkin was knighted in 1906, and received the first ever Perkin Medal of the Society of Chemical Industry, created on the 50th anniversary of discovery of mauveine, the year before his death. 

 

References

William Henry Perkin, wikipedia, accessed February 2021

Mike Sutton, The Perkin family legacy, Chemistry World, 26 February, 2010.

The mystery of the Victorian purple dye, Research Outreach, 2020.

Sir William Henry Perkin 1838 - 1907, Science Museum Group, accessed February 2021 

Brian Resnick,William Henry Perkin: how an 18-year-old accidentally discovered the first synthetic dye, Vox.com, March 18, 2018.