Aerometer
Use
It is used to determine the density of a liquid in a direct way.
Description
It is usually made of glass and it consists of a sealed ampoule of glass, with a ballast at its bottom and a hollow cylindrical tube, which has a graduated scale, at its top. The arrangement of the scale varies depending on how dense the liquid is, denser or less dense than water.
Functioning
It is based on Arquimedes’ principle: when you leave it floating freely in a liquid, it receives an upward buoyant force which is proportional to the density of it. The combined forces of the ballast (denser than the liquid we want to measure) and the air contained in the ampoule (lighter) make the device float partially submerged for a determined range of densities of the liquid analysed.
The division of the scale which coincides with the surface of the liquid shows us the density ot it.
History
It is considered to be invented by Hypatia of Alexandria.
