Baumé scale

noun

: either of two hydrometer scales that indicate specific gravity in arbitrarily defined but constant degrees:

a

: one for liquids lighter than water on which specific gravity S at 60°F (15.6°C) is related to the Baumé reading n in degrees by S = 140 ÷ (130 + n)

b

: one for liquids heavier than water on which specific gravity S at 60°F (15.6°C) is related to the Baumé reading n in degrees by S = 145 ÷ (145 − n)