University of Illinois at Urbana-Champaign
Rare Book Room Exhibit

In 1873, van der Waals obtained his doctor's degree for a thesis entitled Over de Continuiteit van den Gas- en Vloeistoftoestand (on the continuity of the gas and liquid state), which put him at once in the foremost rank of physicists. In this thesis, he put forward an "Equation of State" embracing both the gaseous and liquid state; he could demonstrate that these two states of aggregation not only merge into each other in a continuous manner, but that they are in fact of the same nature. This equation of state was a dramatic improvement over the ideal gas law. It was van der Waals' genius that made him see the necessity of taking into account the volumes of molecules and the intermolecular forces ("van der Waals forces", as they are now generally called) in establishing the relationship between the pressure, volume, and temperature of gases and liquids. This copy of Over de Continuiteit is open to the chapter where van der Waal's equation of state, ( P + a/V2 )( V - b ) = RT, is first derived. Van der Waals won the Nobel Prize for this work in 1910.

Partington IV, pp638-640; Nobel Lectures, Physics, 1901-1921.

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