The term specific gravity, symbolized sp gr, (what about SG?) refers to the ratio of the density of a solid or liquid to the density of water at 4 degrees Celsius. The term can also refer to the ratio of the density of a gas to the density of dry air at standard temperature and pressure, although this specification is less often used. Specific gravity is a dimensionless quantity; that is, it is not expressed in units.

I'm assuming that "at 4 degrees Celsius" refers only to the water in the equation???? Thus, one would calculate the density of ice at whatever temperature and pressure and then ratio it against the value for water to get the sp gr.

stales