Specific gravity is the ratio of the mass (weight) of any given
volume of solid or liquid, to the mass of the same volume of water. To
calculate specific gravity of any given substance, you will need to
choose a given volume and then weigh it. The resulting number,
expressed as weight/volume, is placed in the numerator position of a
fraction, and the weight of the same volume of water is placed in the
denominator position. You will then divide one by the other and end
up with a number referred to as the specific gravity of that tested
solution.
e.g. 1 liter of 5% dextrose in H2O weighs 1.02kg
1.02kg/L (5% dextrose in H20)
= 1.02 which is the specific gravity of the 5% soln
1.0kg/L (H20)
If you weigh one liter (or half a liter X 2) in kilograms, you should
have your S.G.
Steve Fox