#hydrometer__gravimeter  a measuring instrument for determining the specific gravity of a liquid or solid
  supertype:  #measuring_instrument__measuringinstrument__measuring_system__measuringsystem__measuring_device__measuringdevice  instrument that shows the extent or amount or quantity or degree of something
  subtype:  #salinometer  a hydrometer that determines the concentration of salt solutions by measuring their density
  subtype:  #thermohydrometer__thermogravimeter  a hydrometer that includes a thermometer

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