hydrometer

plural hydrometers · alternative nonstandard hydrometre

1. An instrument that floats in a liquid and measures its specific gravity on a scale.

   On the wall were hanging thermometers, barometers, and hydrometers, and every other sort of ometer, numberless, dusty, and mysterious; […]

   1843, John Holmes Agnew, Eclectic Museum of Foreign Literature, Science and Art

   1 more example

   [E]ach degree of the hydrometer, when at or near proof, is about a quart in a hundred gallons stronger or weaker, as the hydrometer vibrates under or over the silver speck or sight on the index or upper stem; at the intermediate or strong overproofs, is about a pint in ditto; and at the low underproofs is about three pints in ditto.

   1806, Peter Jonas, “Method of Ascertaining the Strength of Spiritous Liquors by Clarke’s Hydrometer”, in The Genuine Art of Gauging Made Easy and Familiar; Exhibiting All the Principal Methods Actually Practised by the Officers of His Majesty’s Revenue of Excise and Customs: …, London: Printed [by C[harles] Whittingham] for Dring and Fage, […], →OCLC, page 367

   Synonyms: areometer