It has been shown (Roberts 1935) that the accommodation coefficient of neon with a tungsten surface is very sensitive to the presence of adsorbed films and that changes in it may be used to study the adsorption of traces of gases mixed with the neon. The method has been applied to obtain some properties of adsorbed films of hydrogen, oxygen and nitrogen on tungsten (Roberts 1935; Van Cleave 1938). In these experiments the actual partial pressure of the gas undergoing adsorption was not determined and was not maintained constant. In the present development these two limitations have been removed. The experiments have been made with oxygen, but the new technique is applicable to any gas which is removed efficiently by charcoal cooled in liquid air and it can be used down to extremely low pressures. The essential parts of the apparatus are shown in figure 1. As in the earlier experiments the neon was continuously circulated through charcoal tubes
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cooled in liquid air to remove adsorbable impurities from it.
A new method for studying the adsorption of gases at very low pressures and the properties of adsorbed films of oxygen on tungsten