@property<EOL><INDENT>def SGg(self):<DEDENT>
Vmg = self.VolumeGas(T=<NUM_LIT>, P=<NUM_LIT>)<EOL>if Vmg:<EOL><INDENT>rho = Vm_to_rho(Vmg, self.MW)<EOL>return SG(rho, rho_ref=<NUM_LIT>) <EOL><DEDENT>return None<EOL>
r'''Specific gravity of the gas phase of the chemical, [dimensionless].
        The reference condition is air at 15.6 °C (60 °F) and 1 atm 
        (rho=1.223 kg/m^3). The definition for gases uses the compressibility
        factor of the reference gas and the chemical both at the reference
        conditions, not the conditions of the chemical.

        Examples
        --------
        >>> Chemical('argon').SGg
        1.3795835970877504