Thermodynamic stability of ice models in the vicinity of a critical point

The properties of the two-dimensional exactly solvable Lieb and Baxter models in the critical region are considered based on the thermodynamic method of investigation of a one-component system critical state. From the point of view of the thermodynamic stability the behaviour of adiabatic and isodynamic parameters for these models is analyzed and the types of their critical behaviour are determined. The reasons for the violation of the scaling law hypothesis and the universality hypothesis for the models are clarified.