Adsorption of Helium Four on Saran Charcoal at Temperatures Below 5 °k

Isotherms for the adsorption of helium on Saran charcoal in the region of the boiling point of helium and for pressures above 7 × 10−4 torr have been determined and isosteric heats of adsorption calculated. The average density of the adsorbed helium is 0.249 g cm−3. It is concluded that the first two layers of helium on the carbon are in a solid state while higher layers are a liquid. The view that Saran charcoal contains a system of micropores 10–15 Å in width is confirmed.