Refractometer
Videos
A refractometer is a laboratory or field device for the measurement of an index of refraction. The index of refraction is calculated from the observed refraction angle using Snell's law. For mixtures,
Hand-held refractometer
Bausch & Lomb Abbe Refractometer, ca. 1919–1926
Gemology refractometer ER604 used to test light bending in gemstones; courtesy of A.KRÜSS Optronic GmbH
Relative density
Videos
Relative density, also called specific gravity, is a dimensionless quantity defined as the ratio of the density of a substance to the density of a given reference material. Specific gravity for solids
A United States Navy Aviation boatswain's mate tests the specific gravity of JP-5 fuel
An empty glass pycnometer and stopper
A filled pycnometer