Agnes Pockels, 1862-1935 M. Elizabeth Derrick Vsldosta State College Valdosta. GA 31698
Pockels is aname familiar to many surface chemists; however, most probably do not realize that this is a woman who did much of her experimental work a t home in her kitchen, who had difficultv" publishina her results, and who, because * of discrimination against women in Germany during her early vears. . did not hold a universitv. degree. - Despite these adversities, she made major contributions to the early work in surface chemistry. In short reviews of the history of surface chemistry, her name is always listed along with others such as Ravleiph. Langmuir, Adam, Harkins, and Rideal. Further recoghition is given to her in referring to the minimum area occupied by a monomolecular surface film, about 20A2 per molecule, as the Pockels' point. Agnes Pockels made her publishing debut in 1891, some tens years after she hegan her experimental work. She had been unsuccessful in having her work recognized in her own country and hence, with the encouragement of a younger brother, Friedrich Pockels, a physicist, she wrote to Lord Rayleigh in England.' The first publication of Agnes Pockels' work appeared in the letters-to-the-editor column in N a t ~ r e . ~ The orieinal oublication includes an initial note from Lord FiayleigK expkning the letter which he had received from her. This note is followed hv a translation of Ames Pockels' letter to him. In Lord ~ a ~ l e i g hintroductory 's note, he states, "I shall he 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 a t valuable results respecting the behavior of contaminated water surfaces. The earlier part of Miss Pockels' letter covers nearly the same ground as some of my own recent work, and in the main harmonizes with it. The later sections seem to me very suggestive, raising, i f they do not fully answer, many important questions. I hope soon to find opporrunity for reoearine some of Miss I'ock~ls'ex~erimenLq." The translation of ~ ~ nPockels' i s letter then foliows: My Lord,-will you kindly excuse my venturing to trouble you with a German letter on a scientific subject? Having heard of the fruitfulresearches carried on by you last year on the hitherto little understood properties of water surfaces, I thought it might interest you to know of my own observations on the subject. For various reasons I am not in a position to publish them in scientific periodicals, and I therefore adopt this means of communicating to you the most important of them. After discussing her experimental work the letter ends with:
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I thoueht I oueht not to withhold from vou these facts which I " have observed, although I am not a professional physicist; and again begging you to excuse my boldness, I remain, with sincere respect, Yours faithfully, (Signed) Agnes Pockels.
In the body of this letter, Agnes Pockels discusses the development of her technique for making quantitative mea1030
Journal of Chemical Education
surements on surface films. Her surface film balance technique is the bnsis for the method later developed by Langmuir and often referred to as a Langmuir trough. This technique is.still - used bv surface chemists: Also described are her results from numerous experiments using this apparatus, including her of the so-called Pockels' point. - ~ observation There are only two readily available sources of biographical information concerning Ms Pockels. The Ostwald paper' includes a short autohiographical note by Ms Pockels herself. The Giles and Forrester papel3 includes information and quotes from the unpublished diary of Ms Pockels and from a biomaohical article hv her sister-in-law in an obscure Ger- . man journal. Aenes Pockels was born February 14,1862 in Venice where her Father, a member of the ~ o ~Austrian a i army, was stationed. Her brother, Friedrich (Fritz), was born three years later. In 1871the family moved to Bmnswick in Lower Saxony, and i t was there that Agnes attended school and conducted her experiments during the remainder of her life. She was educated a t the Municipal High School for Girls where, in her autohiographical notes', she states she developed an "enthusiastic interest in the natural sciences, especially physics." She stresses, however, that women at that time were not allowed the privilege of studying further. Later in her life, when women were allowed to attend the university, her parents would not allow it. Fritz did attend the university and later became a professor of physics. It was through him that Agnes obtained textbooks, teaching herself such subjects as differential calculus. The Pockels family apparently had frequent health problems. Aenes. . as the unmarried and only dauphter, assumed the management and nursing responsibilitiesin her parents' home a t an early age and continued to live there throughout her life. Her sister-in-law states3: ~
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Their studies were often conducted in the kitchen where Agnes, being the daughter of the household, had to do her chores and where it was alwavs nice and warm. In this wav. .. , \ p e r made her firrt ubiervstionr in the field of capillarity. This is really true and nu jukc or poetic ltrence: what millions of women see every day without pleasure and are anxious to clean away, i.e., the greasy washing-up water, encouraged this girl to make ohservationsand eventually to.. .scientific investigation. Ms Pockels hegan her earliest experimental work a t about the age of 18and had invented the slide trough by the time she was 20. She was unsuccessful in interesting others in her work until she wrote to Lord Rayleigh, r e s u l L g in the previously quoted publication of her letter. This recognition stimulated her work, and she proceeded to publish thirteen papers in the period from 1891t o 1918, publishing two later papers in 1926 and 1933. In her autobiographical notes in the Ostwald paper1, she explains the disruption of her publishing in 1918 by the advent
' Ostwald, W.. Koll. Zeit, 58, l(1932).
Rayleigh and Pockels. Nature 43, 437 (1891). Giles, C.H.and Forrester. S. D., Chemishyand Indust!?', 1971.43
(1971).
of World War I, her brother's death, and her own failing health. Her brother's university appointment a t Heidelberg and her recognition by Lord Rayleigh ultimately resulted in her work being recognized in Germany. Most of her work was published in German journals. In her later years Agnes Pockels received well-deserved recognition for her work. The previously mentioned paper by Ostwaldl, entitled "Die Arbeiten von Agnes Pockels iiher Grenzschichten und Filme," is a tribute t o her work on the occasion of her 70th birthday. In 1931 she was awarded, jointly with H. Devaux, the Laura Leonard Prize for "Quantitative Investigation of the Properties of Surface Layers and Surface Films." In 1932 the Carolina-Wilhemina University of Brunswick awarded her an honorary doctorate.
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Her sister-in-law states3 that "during these latter years,. she led a quiet life as 'Auntie Agnes,' like many other middle-aged women in Bmnswick. She had many acquaintances, and two puzzle-solving societies met in her home . . .. She herself alwavs lived simolv. . ".and keot her thouehts to herself without sayLg much. The information about cer special scientific knowledge was now onlv noised abroad in whisners." Agnes Pockels died in 1935 a t the age of 73. ~
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"Profiles in Chemlsbv" Is a bfwra~hical feature. hlohllahtlna me " . COnDlblltiMS 01 d.01inguiEhedchemsLs 'n me mnten ofUmir lives. rhe mlumn s designed lor curriculumenrichment. allowing the secondary schaal teacher to snnance the vitalily of chemlslry wrlh the sense of Scholarship and adventure shared by chemists throughout history.
Volume 59
Number 12
December 1982
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1031
