A device used to measure the density or specific gravity of a liquid. The device, usually made of glass, floats in the liquid and sinks to an equilibrium depth according (p. 190) to Archimedes’ principle, leaving a graduated stem unimmersed from which the density or specific gravity is directly read. It is used in the whisky, beer, and wine industries, and can provide an indication of the concentration of alcohol after fermentation and in the distillation of spirits.