The functions entering into the equation of state of Mie-Gruneisen solids are constructed approximately. In [1] an approximate equation of state was proposed for solids whose adiabatic curves obey a linear relationship between the velocity of the shock wave D and the mass velocity U; the slope of the shock adiabatic curve was equal to 1.5. In the present work, the dimensionless variables proposed in [2] are used to construct an equation of state which is free from the above-mentioned limitation. The equation of state found is used to make calculations of the shock compression of porous metals, in particular, of copper, with values of the porosity not differing significantly from unity.