The liquefaction of gases, and the artificial production of low temperatures

Abstract

This is a mainly anecdotal account of some selected chapters from the 100 years history of refrigeration. Much of it is based on my own personal experiences and, consequently, it is far from being a balanced story.I begin with the first liquefaction of oxygen and try to show that the experiments of Cailletet and of Pictet were the forerunners of all future cryogenic methods, even of magnetic and nuclear cooling.The origins of magnetic cooling and its first experimental realizations are recalled next, followed by brief descriptions of some idiosyncratically chosen episodes from the first 20 years of magnetic cooling. This part of the paper ends with a purely personal assessment of the achievements of magnetic cooling and of its future.Nuclear cooling is treated in the same way but there is one difference: most of its history is not ancient but modern and I have therefore made only passing references to the latest developments, leaving it to the practitioners to tell their own story.