Description

An instrument used in the laboratory for measuring the relative density of liquids based on the concept of buoyancy. It consists of a sealed hollow glass tube with a wider bottom portion for buoyancy, a ballast such as lead
for stability, and a narrow stem with graduations for measuring, the liquid to test is poured into a tall container, often a graduated cylinder, and the hydrometer is gently lowered into the liquid until it floats freely, the point at which the surface of the liquid touches the stem of the hydrometer correlates to relative density.