IV. A contribution to the theory of liquid helium II

Abstract

A theory is given of certain properties of liquid helium, in particular The theory is based on London's concept of a condensed Einstein-Bose gas and Bijl, de Boer and Michels' explanation of the energy gap between the lowest state and the excited states. It seems possible to show that, to the approximation to which interaction between pairs of atoms alone is considered, the theory accounts well for the phenomena that. depend on the “two fluid” model of Landau and Tisza.