1. n. [Drilling Fluids]

The curved interface between two immiscible phases in a tube, such as in a pipette or graduated cylinder. Liquid volumes should be read at the bottom of a curved meniscus by alignment of the bottom of the meniscus. For water and liquids that wet the glass, the meniscus is concave. For nonwetting liquids, such as mercury, the meniscus is convex.

See: alkalinity test,  calcium test,  chloride test,  endpoint,  oil-water interface,  retort,  surface tension,  titration