He next experimented with a high-pressure hydrogen jet by which low temperatures were realised through the Joule -- Thomson effect, and the successful results he obtained led him to build at the Royal Institution a large regenerative cooling refrigerating machine. Using this machine in 1898, liquid hydrogen was collected for the first time, solid hydrogen following in 1899. He tried to liquefy the last remaining gas, helium, which condenses into a liquid at 268.9 C, but owing to a number of factors, including a short supply of helium, Dewar was preceded by Heike Kamerlingh Onnes as the first person to produce liquid helium, in 1908. Onnes would later be awarded the Nobel Prize in Physics for his research into the properties of matter at low temperatures -- Dewar was nominated several times, but never succeeded in winning the Nobel Prize.

Who has won the race to liquefy helium? Okie... think carefully first, then make a decision:
The relevant information to answer the above question is: He tried to liquefy the last remaining gas, helium, which condenses into a liquid at 268.9 C, but owing to a number of factors, including a short supply of helium, Dewar was preceded by Heike Kamerlingh Onnes as the first person to produce liquid helium, in 1908. So, the answer is Heike Kamerlingh Onnes.