@property<EOL><INDENT>def SGs(self):<DEDENT>
rhos = self.rhos<EOL>if rhos is not None:<EOL><INDENT>return SG(rhos)<EOL><DEDENT>return None<EOL>
r'''Specific gravity of the solid phase of the chemical at the 
        specified temperature and pressure, [dimensionless].
        The reference condition is water at 4 °C and 1 atm 
        (rho=999.017 kg/m^3). The SG varries with temperature and pressure
        but only very slightly.

        Examples
        --------
        >>> Chemical('iron').SGs
        7.87774317235069