code: def Zs(self):
          r'''Compressibility factor of the chemical in the solid phase at the
          current temperature and pressure, [dimensionless].
  
          Utilizes the object oriented interface and
          :obj:`thermo.volume.VolumeSolid` to perform the actual calculation of
          molar volume.
  
          Examples
          --------
          >>> Chemical('palladium').Z
          0.00036248477437931853
          '''
          Vms = self.Vms
          if Vms:
              return Z(self.T, self.P, Vms)
          return Nonf Zs(self):
          r'''Compressibility factor of the chemical in the solid phase at the
          current temperature and pressure, [dimensionless].
  
          Utilizes the object oriented interface and
          :obj:`thermo.volume.VolumeSolid` to perform the actual calculation of
          molar volume.
  
          Examples
          --------
          >>> Chemical('palladium').Z
          0.00036248477437931853
          '''
          Vms = self.Vms
          if Vms:
              return Z(self.T, self.P, Vms)
          return None
docs: r'''Compressibility factor of the chemical in the solid phase at the
          current temperature and pressure, [dimensionless].
  
          Utilizes the object oriented interface and
          :obj:`thermo.volume.VolumeSolid` to perform the actual calculation of
          molar volume.
  
          Examples
          --------
          >>> Chemical('palladium').Z
          0.00036248477437931853