A stable bath made comparisons possible
Kamerlingh Onnes first liquefied helium in 1908 after developing a system of gas purification, precooling and controlled expansion. The liquid bath gave the laboratory a repeatable route to temperatures unavailable with hydrogen alone.
A reliable cold environment mattered because a material property could now be followed through a temperature interval without rebuilding the entire experiment at each point.
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Resistance changed abruptly in mercury
In 1911, cooling mercury into the helium range revealed an abrupt disappearance of measurable electrical resistance. That sharp change differed from a smooth improvement in an ordinary conductor and opened the study of superconductivity.
A resistance limit is still a measurement limit
An experiment reports how small a voltage or resistance it can resolve at a specified current. Contacts, lead resistance, thermometer calibration and heat leakage matter. Establishing magnetic flux exclusion later added a distinct property to the definition of the superconducting state.
The award covered a research method and its discoveries
The 1913 award concerned low-temperature investigations leading, among other achievements, to liquid helium. The critical-field Lab follows one later consequence: a superconducting state can be destroyed by temperature or field. Its near-transition model does not reproduce the historical liquefier.