Discoveries by the School of Van der Waals and Kamerlingh Onnes by Johanna Levelt Sengers

This book narrates the story of pioneering scientists in the Netherlands, who reached a profound and omprehensive understanding of fluid mixture criticality and phase separation within a brief time span around the end of the 19th century. This achievement was the consequence of the felicitous collaboration of two Dutch physicists and Nobel prize winners, Johannes Diderik van der Waals (1837-1923) at the University of Amsterdam, and Heike Kamerlingh Onnes (1853-1926) at the University of Leiden. Processes of mixing and separation of fluids, underlying almost all production methods in the chemical industry, can be surprisingly complex. Throughout most of the 19th century, the mechanism of phase separation of pressurized fluid mixture remained a mystery. In 1890, Van der Waals, by generalizing his famous equation of state to fluid mixtures, brought Gibbs’s abstract thermodynamics to practical application. The Amsterdam mathematician Korteweg provided the mathematical underpinnings. Van der Waals’ mixture equation inspired a major experimental effort by Kamerlingh Onnes and his collaborators Kuenen, Keesom, and Verschaffelt. They discovered various types of binary fluid phase separation; the Amsterdam chemist Van Laar classified these by means of the Van der Waals equation. Between 1890 and 1906, the Dutch School reached an understanding of phase behavior and criticality of fluid mixtures that was far ahead of its time. Much of their work would be rediscovered or resumed only in the second half of the 20th century, when research on liquids and critical phenomena flourished anew.