Abstract: A method, composition, and device for determining the specific gravity of a liquid. In the method, a sample of the liquid to be tested is contacted with standardized quantities of substances which participate in a reaction that is affected by the level of solute in said liquid. The resulting effect of the solute on the reaction is a reproducible function of the concentration or amount of solute in the sample and relates to the specific gravity of the liquid tested. A unitized test composition is provided comprising at least one substance which participates in the standardized reaction. The standardized reaction is preferably chemical in nature and, in such a case, the test composition preferably includes an indicator responsive to a product of the chemical reaction.