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How Fluids Unmix: Discoveries by the School of Van Der Waals and Kamerlingh Onnes



Johanna Levelt Sengers


This book narrates the story of pioneering scientists in the Netherlands, who reached a profound and comprehensive understanding of fluid mixture phase separation within a brief time span around the turn of the 19th century. This achievement was the consequence of the felicitous collaboration of two Dutch physicists, Johannes Diderik van der Waals (1837-1923) at the University of Amsterdam, and Heike Kamerlingh Onnes (1853-1926) at the University of Leiden. Both were to win Nobel prizes along with several other of their country men of that period, including Hendrik Antoon Lorentz, Jacobus Henricus van t Hoff, and Pieter Zeeman.This period of flourishing science in the Netherlands was coined the Second Golden Age by Willink (1998). He named it in reference to the glorious 17th century Golden Age of the Dutch republic, when Holland became a dominant power at sea, and could boast not only of its unsurpassed school of painters, but also of scientists such as Anthony van Leeuwenhoek and Christiaan Huygens.The second Golden Age of science in the Netherlands did not arise by accident. As is carefully documented in the biography of Van Der Waals by Kipnis et. al. (1996), the way to a scientific revival was paved by the restructuring of Dutch secondary education in the 1860s. Before that time, only gymnasia, or Latin schools, reserved for sons of the privileged, gave access to university education. When a solid middle class of business owners and industrialists began to form due to the upturn of the economy, a need was felt for a more practically oriented type of school, with emphasis on mathematics and science instead of the classical languages. In a862, a non-sectarian, free-market-oriented government under prime minister Johan Rudolph Thorbecke came to power. Thorbecke came to power. Thorbecke had democratized elementary education during an earlier period of governing. During his new tenure, he opened secondary education to the middle class. In 1862, a new type of school, the Hoogere Burgerschool (HBS), or high school for (male) burghers, was signed into law. The 5-year HBS taught a solid curriculum of mathematics and the sciences, in addition to Dutch, three modern foreign languages, history and geography. Curiously, it did not give direct access to university education until more than half a century after its founding. After completing the HBS, students aspiring to a university education had to pass a state (nation-wide) exam in Latin and Greek, which usually took another year of preparation. The new HBS required an influx of well prepared science and mathematics teachers. Improved economic conditions in the country provided the opportunities for the necessary expansion of science education at the universities.Although it was possible to obtain teacher qualification by other paths, many of the new HBS teachers were university-trained, which enabled them, in turn, to inspire their students and open the prospect of a university education for them. On finishing a mathematics or science doctorate, many would find secure, well paid and and respected jobs as HBS teachers, form which they might later graduate to an academic position. As a consequence, a strong interaction resulted between HBS and university science education.As stated by Kippis et al., Almost all Dutch scientists passed through the HBS, either as students or as teachers, or both.' For instance Van der Waals, who himself never had the privilege of an HBS education, let alone a gymnasium, taught HBS for a dozen years before he became a university professor in 1877.In the Netherlands, the HBS, as founded by Thorbecke, functioned largely unchanged until well into the 1960s. Then, as had happened in the United States early in the 20th century, the demand for mass access to high schools led to reforms of the high school teacher eductaion system that ruptured the tie between university education and teacher training. Some ascribe the current
How Fluids Unmix: Discoveries by the School of Van Der Waals and Kamerlingh Onnes
Publisher Info
Royal Netherlands Academy of Arts and Sciences, Amsterdam,


azeotropy, barotropy, binary fluid mixtures, critical points, gas-gas equilibria, history, Kamerlingh Onnes, Korteweg, phase equilibria


Levelt Sengers, J. (2002), How Fluids Unmix: Discoveries by the School of Van Der Waals and Kamerlingh Onnes, Royal Netherlands Academy of Arts and Sciences, Amsterdam, , [online], (Accessed April 23, 2024)
Created August 31, 2002, Updated August 8, 2023