Gladstone–Dale relation

The Gladstone–Dale relation is an empirical mathematical relation used for optical analysis of liquids, the determination of composition from optical measurements. It can also be used to calculate the density of a liquid for use in fluid dynamics (e.g., flow visualization). The relation has also been used to calculate refractive index of glass and minerals in optical mineralogy.

The relation is named after John Hall Gladstone and reverend Thomas Pelham Dale, who published first discussed it in 1863.