ABSTRACT
The year before receiving his doctorate, Ormes had secured a position as assistant to Johannes Bosscha, director of the Polytechnic School at Delft. His four years under Bosscha proved an invaluable training period in designing and handling experimental apparatus. More important yet for the course of his future career were two papers published by Diderik van der Waals, then professor at the University of Amsterdam and with whom Onnes was in close contact. Van der Waals had obtained his doctor's degree at Leiden under Bosscha based on a thesis introducing his famous equation of state for simple gases involving molecular forces. His published thesis, 'On the continuity of the gaseous and liquid states', not only caught the attention of Onnes (who would put the equation of state to good use when he undertook to liquefy helium at a later time), but also impressed Maxwell to the point of going to the trouble of learning Dutch to read it, as it did Thomas Andrews of Queen's College, Belfast-the father of isotherms characterizing 'real' gases. The second of van der Waals' papers to leave its mark on Kamerlingh Onnes was the one in which he introduced his law of 'corresponding states', a paper published two years before Kamerlingh Ormes' appointment to the chair at Leiden.
