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Agnes Pockels
Agnes Pockels

With no formal training in chemistry, Agnes Pockels initially carried out experiments in her kitchen, later being recognised as a pioneer of surface science.

Agnes was born in 1862 in Venice, which at that time, was under Austrian rule. Her father served in the Austrian army, but when he fell ill with malaria, the family moved to Brunswick in the newly-formed German Empire. Agnes was interested in science as a child but her local girls’ school, which she attended, did not have much science on the curriculum.

“I had a passionate interest in natural science, especially physics, and would have liked to study.”- Agnes Pockels*

Despite Agnes's desire to study physics after leaving school, women were not allowed to enter the universities. Her younger brother Friedrich, however, also wanted to study physics and took a degree at the University of Göttingen. By sending letters to his sister and giving her access to his textbooks, Friedrich helped Agnes learn advanced physics from her home in Brunswick. Friedrich became a physicist and throughout his life he sent Agnes letters detailing the latest developments in physics.

Despite her studies at home, Agnes was not able to perform the experiments that her brother could due to a lack of equipment. Nonetheless, her day-to-day activities running her family home provided occasional chances to put her education to good use; legend has it that she became interested in the effect of impurities on the surface tension of liquids while doing the washing up in her kitchen. As she looked after the house of her ageing parents, she had lots of opportunities to use soaps, oils and other products, and to see the effect they had on water.

Not long after, she developed a piece of apparatus called the Pockels trough; although simple, this trough was able to measure the surface tension of water under the influence of different surface concentrations of the oils and soaps she worked with.

After a couple of years of experimentation with the Pockels trough, Agnes received a letter from her brother telling her about a publication by Lord Rayleigh. In this paper, Rayleigh had investigated the properties of a thin layer of oil on the surface of water. Seeing that Rayleigh was conducting similar research to her own, Agnes sent him a letter, in German, with the results of her experiments. She told Rayleigh he could keep her results for himself, but he was so impressed, he had the letter translated and submitted it to the journal Nature under her name, together with an article of his own. He wrote to them saying, “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 respecting the behaviour of contaminated water surfaces.” Nature published the letter, and Pockels’s work became renowned.

She continued to perform experiments in her kitchen, and with Rayleigh’s encouragement, went on to publish several more papers on surface science. Unfortunately the health of her parents worsened shortly after the turn of the century, leaving less time for her to study, and the First World War hit her social and scientific circles hard. She stopped performing experiments after the war, and maintained only intermittent contact with scientists in her field.

The Pockels trough was adapted and developed by Irving Langmuir, who then used it to make several more important discoveries in surface science. He received the Noble Prize for these discoveries in 1932, and in an article he paid tribute to Agnes’s work. Two commentators, Charles Giles and Stanley Forrester, later wrote:

“When Langmuir received the Nobel Prize for Chemistry in 1932, for his work in investigating monolayers on solids and on liquids, part of his achievement was thus founded on original experiments first made with a button and a thin tray, by a young lady of 18 who had had no formal scientific training.”

However, Agnes's work did not go unrecognised during her lifetime. In 1931, she was awarded the Laura R. Leonard Prize of the German Colloid Society, the first woman to win the award. The following year, she received an honorary doctorate from the Technical University of Braunschweig, in honour of her 70th birthday.

Agnes died shortly after these awards, in 1935. Just before her death, the eminent biologist Sir William Bate Hardy FRS, wrote:

“I think I may say without exaggeration that the immense advances in the knowledge of the structure and properties of this fourth state of matter, which have been made during this century, are based upon the simple experimental principles introduced by Miss Pockels.”


* W. Ostwald Kolloid-Zeitschrift 58, 1, 1932 

Words by Stephen McCarthy
Images © RSC Library/ Royal Society of Chemistry
Published November 2014

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