Devices used to measure the density of a liquid; measurement relies on a reference to an appropriate working fluid, such as water or mercury, using an analytical balance.

Pycnometers are used for measuring and comparing densities or specific gravities of liquids and solids, including soil.

What Is a Pycnometer?

Pycnometer bottles are usually made of glass and have a ground glass stopper with a capillary tube for air bubbles to escape. It uses a balance to measure the density in reference to a working fluid like water or mercury.

How Does a Pycnometer Work?

First the weight of the empty flask is measured. It is then weighed when filled with the reference liquid and weighed again when filled with the testing liquid. These weights are used to calculate the relative density of the liquid.

Alternatives for measuring specific gravity include hydrometers, density meters, and refractometers.

Types of pycnometers include:

• Gay-Lussac
• Hubbard