Abstract
By measuring the resistance of a phosphor bronze wire in thermal equilibrium via various substances with crystals of iron ammonium alum it is shown that the time for thermal equilibrium between the ionic magnets of the salt and its lattice vibrations is less than 0·5 sec. for all temperatures above 0·025° T*. When liquid helium or a german silver tube forms part of the cooled portion of the apparatus, the time for equilibrium is increased to a few seconds for temperatures below 0·4° K. It appears possible that the thermal conductivity of german silver is less than 10−8 cal. cm.−1 sec.−1 degree−1 below 0·05° T*, and there are indications that the thermal conductivity of liquid helium at temperatures below 0·3° K. is small compared with its value at 2° K.
Publisher
Cambridge University Press (CUP)
Cited by
12 articles.
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1. John Frank Allen. 6 May 1908—22 April 2001;Biographical Memoirs of Fellows of the Royal Society;2023-09-13
2. Magnetic Cooling;Reports on Progress in Physics;1955-01-01
3. The Use of Liquid Helium in Magnetic Cooling Experiments;Proceedings of the Physical Society. Section A;1949-06-01
4. Thermal conductivity of copper and german silver at liquid helium temperatures;Mathematical Proceedings of the Cambridge Philosophical Society;1948-04
5. Thermal insulation at very low temperatures;Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences;1942-09-24